No luck, any advice?

My husband and I have been trying to conceive for 6 months now, I’m starting to think I’m the problem and I can tell her starting to get concerned. Any advice? The first months we were trying until the 3rd month we were just going to “let it happen” we’re now going onto 7th month and realized it hasn’t happened. Anything you guys can advise to do different? We have intimacy like crazy, so I’m not sure? Also been looking into opk kits, how would I use that? Thank you