My bladder was very very full, so don't think it's the case... Yeah I will have another ultrasound at 16 weeks and at 20 weeks.
I also think the placenta would be fine if your baby looks good. Your baby is getting his/her food through the placenta so it should be all good. Next times drinks lots of water before your ultrasound, this will help the technician locatext placenta better. Goid luck dear!
Are you getting another ultrasound at 20 weeks? If so he is probably just checking on baby and not worried about it because the baby looks fine and the placenta isn't usually what the Dr is worried about that early on. They normally will do the full anatomy scan including the placenta at 20 weeks when you are far enough along that any defects could be spotted.