Pulse in lower belly?


At 12 dpo today, I’ve been feeling my own pulse / heartbeat around lower abdominal area a lot for about a week now. It is strongest when I lay on my side, sometimes even extending down to the upper legs. I feel it occasionally just sitting in a chair as well. I try not to symptom spot, as I’ve experienced most “symptoms” but never been pregnant, but this is definitely a new one. Could it mean something? has anyone experienced this before BFP? Tested negative yesterday.