I've had the same. I'm now 14w2d and feel them now and then

It could be! I'm 13 weeks and 2 days with my second pregnancy and I am pretty sure I have felt baby on the odd occasion. Like just the night before last I was half away at night and flipped from my back to my stomach quickly and felt a funny flutter in my abdomin that didn't feel like anything normal. And while it doesn't happen often I've felt the odd movement like that on random occasions in the last week. At this point I can't say with 100% certainty it WAS baby. But I'm pretty sure it probably was as it couldn't have been gas or tummy grumbles... it was a different feeling.

It is probably your uterus, I have had them too but probably not the baby right now unless this is not your first.