Is this normal? Plus size 2nd time mom

Second time mom here, my first will be 10. I am currently 18 weeks and 5 days. I THINK I felt the baby randomly but nothing definite. I am a plus size woman (about 294) and was under the impression that I would feel the baby sooner. I haven't thought I felt the baby in about 3 weeks, but had a doc appointment last week, baby's heartbeat was solid at 147 bpm. This Friday I go for my anatomy scan, is it normal for me to fear the worst? I feel like I'm going to go in with my son and my mom, and they either can't tell what the baby is OR even wlrse, the baby isn't alive? I just feel like me being plus size shouldn't affect me feeling baby from inside, but I think I should be feeling stuff by now...