keep learning on the short or not?

hey i just got a 6'10 board from some guy and im 6'4'' 180. i went surfing the other day for the first time at cocoa in florida and it was harder than i thought so i started looking at beginner tips and everyone is saying get a longboard its easier to catch waves.. but my problem isn't catching the waves because i caught like almost every wave i went for and stood up and rode very slowly and wobbly like 7 waves outta like 70 trys lol. so my problem seems like speed/balance (kinda feel like once im up and i stick like im in goo and slowly start to sink as i go or just lose speed) and popping up quick. should i stick it out and keep trying on the short or save up for a long? did anyone else learn on a short? and if i stick with the short does anyone got any tips on where my front and back foot should be once i get up and how my stance should be? o yeah and also do you try to go along with the breaking wave when you get up, or do you just go straight forward when learning.. sorry for so many questions lol, just trying to get this down. i had hellla fun, but i just felt kinda gay sucking so hard, im use to pickin up sports quick and easy but surfing is pretty challenging.