I'm pretty positive I'm having one child but I can't brush off this twin intuition I have.

We've already had our 1st ultrasound (only saw one baby) but wasn't informed much but was just told the heartbeat and the babys actual due date.. turns out I found out I was pregnant in the beginning of my 3rd week. Well when my husband and I went into the 15 week appointment to hear baby's heartbeat (baby is always on the left) well this time they detected baby on the right (I know baby's can move from left side to right) but what's odd about this is I felt baby moving on the left (it could be possible gas)but the Dr. Had a look of uncertainty. This is my 1st pregnancy so I'm unaware of the differences.

P.s. My breast milk came in last week and I'm only 4 months in. My ob said it can happen to most moms so I shouldn't worry anyone else ??