I have worked with plenty of people 300+ pounds, and I actually worked with a 17 year old that was 252 lbs and lost about 40 pounds working with me and is continuing on with her healthy lifestyle!
I know it seems daunting and like it will take 'forever', but it really does NOT take that long once you change your lifestyle! :) It sounds like you are committed, so all you need is the proper tools, and you can be at your 'goal' weight in 10-12 months...and maybe even sooner.
That might sound like a 'long' time, but when look at the fact that you would then have the opportunity to enjoy a fit healthy body for the next 70+ YEARS of your life...doesn't sound so bad now does it! :)
There is NO quick fix. There is no magic pill. I have worked with lots of women that have had the 'weight loss surgeries' and those surgeries only worked for the first few years, but 6-10 years later, they were back where they started, but with a permanently damaged body due to the surgery.