I too noticed an increase in my appetite when I started vaping. I was just plain HUNGRY all the time.
Im no MD (just play one on TV), but I think it is because vaping, in general, does deliver less nicotine to the body!
Now before there is a huge uprising, (I know strength of e-juice, device, and atomizer will all influence nicotine delivery), but I am just speaking " in general terms here".
Nicotine is a stimulant, hence an appetite suppressant. Generally people who are fortunate enough to quit smoking do gain weight.
A few personal theories on that is the decreased level of nicotine in the system, boosting appetite, an initial decrease in metabolism after quitting, and possiblly over eating (frequent snacking) to fufil that oral fixation no longer being met by the hand to mouth routine of smoking!!!
Just my

Take it for what its worth.......free opinion

Your body will get used to the new routine and your appetite and weight will stabilize.
Congrats on making the transition, keep it up!