Your low self-confidence is killing you.
It's a rut that's hard to get out of, but there's good news on the flip side of that coin... High self-confidence is a hard rut to get out of too.
You've lost a hundred fucking pounds man. You saw an obstacle and smashed through it. Doing that builds character. This is just another obstacle.
I tell friends of mine that have shown really, really bad AA to do one simple thing. When out and about, when you see an attractive woman walking toward you or is facing you (can see you peripherally), I want you to give her a genuine, warm smile, and do not take your eyes off her until she looks up. 9 times out of 10, she'll smile back. Even if she doesn't, maintain that eye contact and smile for a few seconds but definitely maintain it if she does.
Keep doing this (not to the same girl, silly) until you get the confidence to say hi. Once you can do that, stop and talk for a bit. You're already walking somewhere, so you've got your time constraint in place, and just say hi. If you're feeling frisky, ask if she'd like to grab some coffee sometime. (Yes, this sounds AFC, but it's a pretty safe approach for day-game and I use it to this day successfully.)
For someone such as yourself, who overcomes huge roadblocks just because you want to (like losing 100 pounds), the sky is the limit. In fact, I really don't see this exercise taking you more than a couple of days.