Increased heart rate?

Ashley • 💏💍Married 7-16-16. 😸😸Cat mom. 💓👶Amelia 10-11-18

I am 11 DPO, in my 8th cycle TTC. Around 9 DPO my heart rate increased from around 70 BPM average to 85-90 BPM. I thought it was from caffiene consumption so I cut my morning coffee the last couple of days but it hasn't gone back down to my normal range. I just had a full physical 2 weeks ago with a full blood panel done and everything was within normal range. I eat a vegetarian diet and, with the exception of a couple holiday meals, I tend to eat healthy and mostly clean. I work out fairly regularly. I'm not worried about it being illness or an infection. I'm still getting BFNs because it's still pretty early.

I brought it up at my family Christmas to my mom, who is a nurse, and she thinks it means I'm pregnant.

Did anyone else have an increased heart rate early on like this or is she just being a wishful grandma? I guess I didn't know it was a symptom! Thoughts? Help?