Well, you're too young to even be messing with steroids IMO. People can argue with this all day long, but there's a good chance your body is still in somewhat of a fragile state...too fragile to handle a large influx of hormones. Of course, there's a chance it may not be, you may have fully matured but I would have my doubts. Personally, I'd give it a couple more years.
Anyway, as for the question, sure, you can still have kids but your odds go down if you stay on non-stop and they'll continually go down the longer you stay on. Further, staying on non-stop year after year...I don't care what half of these idiots on this board say, there's no need for that. For crying out loud, pro bodybuilders, some of the biggest steroid users on earth, most of them come off for a couple months a year...why can't you?