Baby's heartbeat decreasing?

Werdah

Hello all hope you are well. I just had a quick question about baby's heartbeat and if any of you went through something similar and it was no issues. My baby's heartbeat has always been around 150 BPM (12-17 weeks). Three weeks ago it was, last week (18 weeks) it was around 140 BPM and this week (19 weeks) it is around 130 BPM. Is this normal? When I asked my midwife she seem to brush it off and said it's still within normal range and baby is probably sleeping but for some reason it doesn't sit right with me? It doesnt feel like a normal pattern? I do have anxiety so maybe that's why I'm overthinking but something isn't sitting right with me. Did anyone else go through something like this? I'm 19 weeks