I'm sorry I can't be of much help in understanding the side effect of past steroids use, but I can say that unprotected sex in itself might not be enough to get pregnant. You are only fertile for a few days a month, plus your chances of conceiving are only about 25% if you have sex during those times (and you don't drink alcohol or caffiene and you don't smoke).

If you know that you've had sex during your fertile window every month for the last two years, then I suggest trying to visit an RE (fertility specialist). They can answer your question about past steroid use. It sounds possible based on what they say about the side effects of being on steroids but I don't know how long those would last once you are off steroids.