Lifelong obesity/Anterior pelvic tilt. Can I be taller than I actually am?

I am 6’0 (or 5’11.875) 76 inch wingspan 9.1 inch hands (abnormally large proportions for 6’0)

I am 335lbs and 22 years old. From age 18-21 I sat in an office or at home for 90% of the day. The skinniest I was in the past 10 years was 225 at 16 years old.

I got a new job 3 months ago and I’m far more active. About 25 lbs down. It feels like there’s a massive weight in my spine anytime I force good posture. My ass hangs out and my stomach hangs forward like an anterior pelvic tilt. There’s an obvious curve in my spine and I have chronic backpain.

When I lay down, I am the same exact height as my 74/6’2 inch bed.

I also have flat feet. I saw that obesity causes flat feet + spinal compression + an APT which worsens this height loss

Am I getting somewhere or am I schizo?

My plan is to get to sub 200lbs and do core/posture exercises on top of normal exercise