Apology help

So I got to see my big brother, sister in law and 2 year old niece this weekend! I was so excited to see them and talk with my sister in law. You see we have both been trying to get pregnant and I just saw a specialist, well when they got there my niece was wearing a T-shirt that said “soon to be big sister”. My response was not great... I just started crying and feeling sorry I guess for myself. Now I am really excited for them and I want them to really want them to know that I told them but it still felt uncomfortable. So any advice on apology ideas? I feel like an asshole