I noticed them a few times during the week but wasn't sure if that's what it was :)
I noticed them every once in awhile at 15 weeks too! (: first really distinct one, I was at work and it was like a gentle stroke up my belly. Didn't feel them every day until 20 weeks (and my placenta isn't at my back, I just have a small stomach even though I was 5'5" and 170lbs pre-pregnancy. Though a lot of that was muscle)
I keep feeling flutters in my belly, I didn't want to ask my mother in law cause I didn't wanna sound crazy lol. They aren't frequent but I usually notice them later on in the day.
No it's possible , every pregnancy is different :) I felt them too at 15 weeks they say if your placenta is at your back then you will feel kicks earlier :)