Upset

I was so excited when I noticed I was 3 days late cuz that literally never happens to me. I took a pregnancy test and it came back negative I was so hurt. Because I wanna give my fiancé a baby so badly he accepts my son as his own. But he really wants one of his own he has no kids he just turned 28 in February. He thinks that he can’t have kids but he got someone else pregnant way before we met. Ion know if it’s me or him but with me it takes a long time for me to get pregnant. I was totally shocked when I got pregnant with my son it just hurts so bad that I might not be able to give him a child. We were thinking of going to see a specialist for the both of us but I’m scared of the outcome. I don’t know what else to do please does anyone have any good advice. I could really use it right now I love him with every fiber of my being I just really want to give him a baby. He truly deserves it he’s a great husband and most of all a wonderful father figure to our son. We’ve only been together for almost 8 months but I feel like I’ve been with him all my life.