Jennifer, I'm confident that you have figured out your problems with snowboarding in that line above.
Lost 120 pounds in 5 months? My dear, you are learning your new body while you try to learn snowboarding. Absolutely you are getting used to controlling your muscles/joints in a different way from what you are used to. If you are still losing weight, your strength is probably not as high as it might be otherwise.
You've received alot of good advice in this thread. If you're fed up spending money on lessons for the instructor to watch you fall, Snowolf has kindly provided links to his online lessons. Use those and ride by yourself for a bit, or find another newbie on the hill to ride with you. DEFINITELY get some padded shorts (Skeletools and Azzpadz seem to be favoured by Forum members) and wrist guards. And yes, I would get off the bunny hill in favour of a moderate green run to at least make side slipping easier.
But don't give up. Once you get used to your new body, I'm sure you will enjoy using it in such a fun sport!
I agree with this^ do not give up. I almost did when i was learning cuz i was tired of eating it, but it became a challenge for me and i wanted to know if i can snowboard. protective gears is a must have. I have to admit though, i never took a lesson but i did watch a lot of snowolf's vids,ask for advices on this forum, snow addiction(SA), and other random vids. kindda learned how to do toeside turn with some helicopter spins
on the bunny hill. But what helped me was getting off the bunny hill on to a mild green run where i can actually have more room to turn. It is intimidating at first but you have to focus on what you need to do. lastly as someone mentioned, when you get tired take a breather. Patience and Willpower(which you already have) is the key here, then it will click on like a light bulb. once it does, the fun begins
btw, reverse cambered boards does make it easier to do spins, LOL!