Hello moms, could you please tell me, I had one delivery before, my da…

Hello moms, could you please tell me, I had one delivery before, my daughter is already 8 and a half months old, I haven't had my period for a while and my belly feels like I'm pregnant again. Could you please tell me if a pregnancy test will be reliable during breastfeeding? I mean, I'm really scared of giving birth with such an interval, after kidney stone three years ago I can't give birth, and now my immunity is weak too.