I feel my stomach twitching all the time, but I can never tell the difference between gas and baby either!
I felt my bby at 16wks...they were little flutters. But usually you can feel baby from 20wks & so forth.
Its different with everyone I felt my baby at 16 weeks but some don't feel them until 24 to 28 weeks
I started feeling my baby move about 19-20 weeks. You should feel little twinges periodically and they'll get more frequent. That should be baby moving. Good luck babe. X