Trying to get pregnant

My husband and i for the last 3 or or so years been having unprotected sex not looking for our next child or anything but lately this year I have a strong Need to get pregnant and I feel crushed that i haven't gotten pregnant yet. I thought a few days ago I was feeling symptoms I was nauseous and three up a couple times but when I took the test it was negative . that's when I knew how truly sad and crushed I felt and finding out my sis in law is pregnant with her second child although I'm happy for her I feel hurt for myself more so cause i don't know if my husband truly understand my feelings towards my wanting to have a baby.