Could also be water weight as well. Be careful about what water you drink, some bottled waters have Sodium Bicarbonate. Which causes you to retain water.
Bloating. My weight jumped really fast when I found out and then settled back down from bloating and body making room
Yeah I'm 4'11 and gained weight kinda fast but pretty much stayed at the same weight for a while after gaining it
It could be because you were so petite to begin with