I've been playing for two months and I've never had a problem with distance despite being 5'11" and 160 (stringy ectomorphic build). I can get well beyond 400' most days. If there's a recognizable thermal it's closer to 500'.
I attribute my freaskish distance to having having a fast run up, followed by a violent snap. If there's not much in my way I'll capitalize on this and throw with a 2 finger grip and really let 'er rip.
This causes the disc to have an absurd amount of spin. With the slightest touch of annhyzer you'll get a super late fade and shots that in my opinion are less accurate but more capable in terms of distance than anything else I've seen. That being said you really need to be careful not to torque it when doing this. It took me 2 weeks to really gain control of the 2 finger release.
I know I'm new and have played much less than you but I've seen this before in my heavier friend who started playing at the same time I did.
I would work on your run-up. Your x-step seems to be nice and snappy, but you're moving forward so slowly it's all you got. If you think your ankles can't take a fast run-up you should try using a blizzard destroyer or some other lightweight disc and annhyzer the **** out of it to milk every last drop of hang time. I've seen players here also use disc with -4/ -5 h/s turn ratings and throw power grips on an almost hyzer line off the tee with pretty much no run-up. This seems to get them a little more distance for whatever reason.
