Welcome to the forum.
SMH, number one who cares what other people think about you on the hill, if your having fun that's what matters. As far as slowing people down, EVERYONE has bailed on a jump multiple times it just happens, as long as you don't take forever to get out of the way afterwards. I've never had an instructor in 14 years so I wouldn't say you need one but maybe that would help build your confidence to start trying some stuff in the park. If you want to compete though you need to start practicing and be ready to take a beating, regardless of which event. Honestly though you've only been riding for 2 YEARS, it takes time to work your way up in skill level. As far as your board length goes I think you should stick around there especially if you want to focus on jumps because it will be more stable for landings but if your really light then you might want to go to a slightly shorter board.
When I was in the Army I knew a man who had 3 rules about sex, one of them was "quantity not quality". I really regret not asking him what 200 pound twins would classify as.