Firstly:
What you did with the servant woman is haraam and is not permissible. A servant woman is not a slave woman whom it is permissible to touch and have intercourse with. A servant woman is free and is not permissible for you except through marriage, which is what you did, but unfortunately you did it late.
The contract that existed between you and the servant woman was a contract of employment, which was to serve you in your house. It was not a contract that permitted you to have intercourse with her. You say that she agreed that you would be her master and she let you touch her and look at her, and that you freed her from the contract, but this has no basis of validity in sharee'ah in the sense that you refer to. A free woman cannot become a slave unless she is a kaafir woman from a state that is at war with the Muslims and the Muslims have captured her. This does not apply in the case which you are asking about.
Secondly:
Slaves (men and women) may be taken in the wars that take place between Muslims and kaafirs, not in wars that are fought amongst the Muslims at times of tribulation.
Islam limited the sources of slaves which existed before the mission of the Prophet (peace and blessings of Allaah be upon him) to just one source, namely slavery resulting from capturing prisoners from among the kuffaar, including women and children.
Shaykh al-Shanqeeti (may Allaah have mercy on him) said: The reason why a person may be taken as a slave is his being a kaafir and waging war against Allaah and His Messenger. If Allaah enables the Muslims who are striving and sacrificing their lives and their wealth and all that Allaah has given them to make the word of Allaah supreme over the kaafirs, then He allows them to enslave the kuffaar when they capture them, unless the ruler chooses to free them or to ransom them, if that serves the interests of the Muslims.
Adwa' al-Bayaan, 3/387
Thirdly:
The mujaahideen take possession of slave women as they take possession of the spoils of war. It is permissible for the one who gains possession of male or female slaves to sell them. In both cases - owning a slave through battle or through purchase - it is not permissible for a man to have intercourse with a slave woman until after she has had one menstrual cycle from which it may be established that she is not pregnant. If she is pregnant, then he must wait until she has given birth.
It was narrated that Ruwayfi' ibn Thaabit al-Ansaari said: I heard the Messenger of Allaah (peace and blessings of Allaah be upon him) say on the day of Hunayn: "It is not permissible for any man who believes in Allaah and the Last Day to irrigate the crop of another else - meaning to have intercourse with a woman who is pregnant. And it is not permissible for a man who believes in Allaah and the Last Day to have intercourse with a captured woman until he has established that she is not pregnant. And it is not permissible for a man who believes in Allaah and the Last Day to sell any booty until it has been shared out."
Narrated by Abu Dawood, 2158; classed as hasan by Shaykh al-Albaani in Saheeh Abi Dawood, 1890.
Fourthly:
It is permissible for there to be a physical relationship between a man and his female slave just as there is between a man and his wife, unless he marries her off to someone else, in which case it is not permissible for him to have intercourse with her because it is not permissible for a woman to be in an intimate relationship with two men at the same time.
Fifthly:
There are no limits with regard to the age difference between a man and his female slave, apart from the fact that it is not permissible for him to have intercourse with her until after she has become able for that.
Sixthly:
The relationship between a man and his female slave should be announced publicly and not kept secret. That is because there are rulings that stem from this announcement, such as if they have children, and so as to ward off any suspicions that people who see them together may have concerning him and her.
Seventhly:
The Prophet (peace and blessings of Allaah be upon him) owned some male and female slaves, among whom were the following: Ibn al-Qayyim said:
Zayd ibn Haarithah ibn Shuraaheel, the beloved of the Messenger of Allaah (peace and blessings of Allaah be upon him). He freed him and arranged his marriage to his freed slave woman Umm Ayman, and she bore him Usaamah. His other slaves include Aslam, Abu Raafi', Thawbaan, Abu Kabshah Sulaym, Shaqraan (whose name was Saalih), Rabaah (who was Nubian), Yassaar (who was also Nubian and was killed by the 'Arniyeen); Mid'am and Kirkirah (another Nubian) - these two were killed at Khaybar. They also included Anjashah al-Haadi and Safeenah ibn Farookh, whose real name was Mihraan, but the Messenger of Allaah (peace and blessings of Allaah be upon him) called him Safeenah (= "ship") because they used to make him carry their luggage when they traveled, so he said, "You are a ship (anta safeenah)." Abu Haatim said that the Messenger of Allaah (peace and blessings of Allaah be upon him) freed him; someone else said that Umm Salamah freed him. The Prophet's slaves also included Anasah, whose nickname was Abu Mashrah; Aflah; 'Ubayd; Tahmaan - also known as Keesaan; Dhakwaan; Mihraan; Marwaan - although it was said that this was another name of Tahmaan, and Allaah knows best; Hunayn; Sandar; Fudaalah (who was Yemeni); Maaboor (who was a eunuch); Waaqid; Abu Waaqid; Qassaam; Abu 'Usayb and Abu Muwayhabah.
His female slaves included: Salma (Umm Raafi'); Maymoonah bint Sa'd; Khadrah; Radwa; Razeenah; Umm Dameerah; Maymoonah bint Abi 'Usayb; Maariyah and Rayhaanah.
Zaad al-Ma'aad, 1/114-116
Eighthly:
It is rare nowadays to find slaves in the shar'i sense in which it is permissible to be intimate with them etc. That is because most of the Muslims have long since given up the obligation of jihad for the sake of Allaah, in addition to their position of weakness and humiliation before their kaafir enemies, so that many of the majority-Muslim nations have signed the protocol that expressly forbids slavery and strives to put an end to it, which was agreed upon in the United Nations in 1953.
Based on that we must be very careful in examining any case where people are bought and sold as slaves, and we must also beware of the misinterpretation of the word amah (pl. imaa') (= slave woman) which some new Muslims understand to mean that enslavement takes place simply by paying the woman some money and agreeing to have intercourse with her. This is like prostitution which is now widespread in some immoral places, night clubs and telephone sex services.
We ask Allaah to help us and you to be patient with regard to matters of our religion and to protect us from falling into evil.
And Allaah knows best.