Im a bit worried

I'm 20 years old about to be 21 in December, my boyfriend of 3 years is 21 turning 22 in October. I have a 3 year old son that's not biologically his. I had my son at 17. Me and my boyfriend are extremely sexually active and we don't use protection. We've been trying to have a baby for the past 6 months now. I'm worried there's something wrong. It's the one thing he wants the most and I'm scared I can't give that to him. Does it take this long to conceive? Am I being paranoid?