Actually what you are feeling is the baby's hiccups!!!! I have this too. Baby's get hiccups and they feel like a hb in the lower belly.
Omg I was about to look this up lol. I noticed mine at 14 weeks and im kinda annoyed with it cause i only notice it when im trying to sleep
Funny I noticed this the other day too at 15 weeks!
You have a HUGE artery going right into that area to feed the lower body, its called the decending aorta. I can always feel mine. I could feel mine when I wasnt pregnant also, if I would lay down on my belly, its weird but its totally normal. I can feel my femoral pulses sometimes too, which is equally as weird:)
It's due to increased blood flow, especially to that area. You have to remember that you make 2x the amount of blood you did before pregnancy (which is why pregnant women are so prone to anemia as well)
I feel mine 2. I asked a friend n she felt her son though the entire pregnancy...so I guess its normal