Smaller platters are easy enough to make, larger platters do require that little extra attention. there's several factors to consider including overall thickness and form as well as the stresses created when turning a piece. I produced a short while ago a sycamore platter measuring 18" diameter which took a while to turn from an 18" x 2" blank. getting the foot and recess was fine, finishing wasn't a problem but when it came to the platter face, after a while of scraping and cutting, it had a slight issue of wanting to curl even with a 1/2in wall thickness.
I would say, give larger platters a try and enjoy yourself.
I've every confidence that you can turn what your mind puts to you. I can happily give some advice on good turning methods, ideas and interpreting ideas to production as well as your market so see this as a good chance to go for it. Sorry I can't comment on photos lol but I reckon you've got a good piece. Call it a blind turner's intuition lol.
have fun.
lew