Is it the baby moving?

Erica
I'm 17w5d and every now and then I feel like a pulse in my belly. It's not like a heartbeat or anything, it's a lot stronger than a heartbeat, and not that frequent. I was just wondering if this is the baby moving
When I put my hand on that spot I can feel like a little thump. I really think it's the baby, but now 100% sure