Definitely try to get a semen analysis done. You may be blaming yourself for no reason. Also, you should get some tests done too.
We've been trying for 3 years as well and it just wasn't working out. Ive just recently been diagnosed with pcos and although I do get my period, I am not ovulating. Im 24, I have a 5 year old and my previous obgyn kept telling me I was fine, that it would happen when i least expect it. Nope! He was wrong. I switched Drs got blood tests done which came back that my insulin n testosterone levels were easy too high. Had more tests done and after learning about pcos I asked him about it, he had me go for an ultrasound and more testing and sure enough that's what I had. Speak to your obgyn and see that he can do
I would recommend him having a semen analysis done. And I agree with Rhiz, with the ovulation predictor tests. I would definitely have him checked though. I cannot stress that enough. I went for years thinking it was myself because I have a lot of female problems and after years of getting those worked out and still not conceiving my husbands semen analysis came back with very very low sperm count, bad motility and bad morphology. I wished we had not of wasted those years and had him checked from the get go.
Best of luck to you. :)
Maybe your missing your fertile window. Have you tried using ovulation predictor tests? Good luck.