I'm ready to give up!!!

I been trying for over 8 years and nothing my hubby feels like we are not a match.but I feel that it's him that's not trying as much as he should with me. If we have sex for the day that's it for him, we do it the most like two times for the week and some week will go and nothing.I have three kids and he don't have any, since we got married we been trying and nothing. I'm so stress out about this and ready to give up. We try everything in the book and went to doctors and they said I'm ok and he is ok, but what stopping us. We even went as far as going to the island to get a bath thinking someone could be hating on us and wants us not to have any kids. I just don't know what to do anymore. I stop taking all the medication the doctors give cause it was not helping us at all. I even help a friend of mine get pregnant because she was trying too and now she having a baby and I'm not. So mad right now!!