Hit puberty pretty late, went from average body type to very very skinny, will i fill out eventually to where i was before (in stage 4 puberty)?

Unsure: To be very skinny after being average body size with puberty growth is unusual, unless your growth spurt was very rapid or you had inadequate calorie intake. It may take a few years for your adult muscles to form if you had late puberty and you may find that weight lifting will help build muscle and change your appearance. Either way, I recommend scheduling a routine physical to address .