I started diving at the 300 lb stage (5' 11") and an XXL BCD - but a back inflate wing model, 5X wetsuits (they are small & don't use the normal sizing for clothes).
After a couple of years and about 100 dives - I switched to a BP & Wing - and believe me, there's no going back after that. I even put the SS plate in my carry on when traveling to the Carib to dive!
I agree with oly5050 ( I use that camera myself!): you have to be comfortable in the water and capable of moderate to strenuous activity - depending on where you dive. My diving ranges from 39 degree quarries to 68 degree NC off-shore to 80 degree Caribbean diving. Therfore exposure protection varies from drysuit to wetsuit to a T-shirt and trunks. If you need a wetsuit - it'll probably have to be custom made - and it sounds like you're on a quick weight loss program - so 50lbs is easily the difference between a wetsuit working correctly (minimizing water pumping/circulation around the body) to just a bladder passing cold water over you body with every kick.
Also - the combination of "bioprene" and neoprene will require significant amounts of weights, especially initially, as all new divers tend to retain extra air in their lungs until they relax after 20-30 dives.
I can second the recommendations above for suppliers - both are good sources - you can also try Divers Supply - if Hartsville is the SC one, there's a store in Charlotte, NC.
At this stage, the most important decision is picking the right LDS and instructor - they'll help guide you with this process.
PM me if you want to share more details, etc.
Good Luck!