Anthony - congratulations on your decision to make a change in your life style - I realize it's been a long journey to this point and will continue to take dedication to accomplish your goals, including returning to diving. I have battled with controlling my weight for years, but sometimes 'fall off the wagon' and find I must rededicate myself to being healthy.
While I haven't gone through gastric bypass, about a year ago I suffered a 'widow maker' heart attack and had a stent, then 3-1/2 months later a pacemaker implanted. A month after the pacemaker, my 2nd cardiologist [I fired the one who had the pacemaker put in], released me, scheduling a regular check up in 6 months. When I asked him about diving, he replied, "you know I can't tell you can dive, the liability, your heart's in good shape, I'll see you in six months." He knew I was going to Fiji this March, but he didn't know, in 2 weeks I'd be in Maui doing 5 dives, including Molokini back wall [100+ fsw], and the Carthigenian [90+ fsw]. I also made a trip to Belize prior to going to Fiji. I returned from Fiji, and went for my check up. I had made over 80 dives since my release, my cardiologist hobbled into the exam room on crutches, broke his fibula, snow boarding.
I've had friends tell me, "you need to slow down", "you can't do the things you used to do". BS, you gotta do what you wanna do, don't live your life for others, make yourself happy. As divers, we've all 'killed many trees' signing release forms basically stating, we assume SOLE responsibility for ANY/EVERY-thing that can/will happen while diving.
You know the fitness level you need to dive, I'm sure you're working to make that level. DAN will tell you need to reach and maintain a level of 13 MEPS [result of a formula including body weight & heart rate, measured during a cardiac stress test] in order to dive. If this requirement was strictly adhered to, 95% of divers wouldn't be able to dive. Once again the decision & the responsibility is yours.
Yes, prior to your first dive 'back', you'll be nervous, & apprehensive, similar to your first dive after being certified. As you did after being certified, start with an easy one, and rebuild the confidence you once had. It won't take long, you'll be back to wanting to make more dives and longer trips. We're all AQUA-HOLICS!!!
I hope this helps. Take care. Dive safe.
Bill
[ps. all you need to know is in my signature]