agree that it is probably the baby. My belly is super lopsided this pg- my right side is noticeably bigger than the left and I feel the "bump" you were talking about only on the right side. At my US, both of my babies were curled up in my lower right uterus. The tech thought it was hilarious bc they have tons of room and fluid so they could move if they wanted- they just don't.
I rarely feel movement on the left side.
I do think, if you have had any ultrasounds of your uterus ever that a heart shaped uterus would have been picked up, but IDK for sure
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ETA: could be where your placenta is, too. Both of my placentas are right sided and I have an anterior wrap, so I think that contributes to looking lopsided