Glass man to Ironman

After suffering long enough i decided to get my stroke looked at and see where im going wrong, an after viewing myself on cam i can see why! I really look like im struggling...so now the coach is going to give me some pointers and where i should be working on, i would upload the video but due to other people in shot underwater i cant without their permission, i was due to do it in an empty pool but thanks to Lincolnshire county council blocking the road of for repairs i was 30mins late to the pool, but im just glad i got it done :-). Also i now own a wetsuit! See the pic below, feels a tad tight so going to loose a few lbs an see if that helps, if not ill have to get another.

I really don't get it, give me a bike or some road to run on and ill do it no probs (when I'm not injured running wise ;-) )....drop me in a pool and 8 laps later im dead and need a rest! Ive tried to slow my stroke down (don't work I sink), I try kicking hard (keeps my legs up, but dead after 2 laps), tried breathing on one side only (no difference)....keeping my head down and my feet breaking the water...but no, I just cant do it.. and have to revert to breast stroke, which at the moment is killing my right hamstring. I think I'm going to have to get my stroke analysed at my tri club and see where I'm wasting all my energy, whats slowing me down and getting me worn out so quick, time is not on my side and I need to be able to do that 1500m pool swim or I'm going to be crapping my pants come Dambuster in June! Or it could be just a case I'm on leave from work and just eating crap most days, not getting the right fuel to power these work outs? who knows?