On June 3rd, I was hit by a car on my Ridley Fenix. I broke my ankle on both sides, my leg fib/tib, and my shoulder. The good news is that I survived the accident, the bad news is my Ridley Fenix did not. The seat tube and fork broke and was beyond repair.

Insurance paid for a new bike and I'm starting to get on the bike using a trainer. I got a fit on April 24th on my old bike, but I'm not sure if I should use those measurements now.

Should I flip my stem up and ride my bike on the trainer in a more up right position or should I stay with the fitting measurements which are much lower?

Check leg length on the leg with tib/fib break.

Is your current position on the bike trainer comfortable? Stick with it, if YES.

I have more pressure on my hands. I think it maybe because I don't have the core strength I had before the accident.

I'm 6'4" and my bike is a 61cm. I have a long torso of 26" and 36" inseam. I have the saddle all the way back and I'm at KOPS. I do have another seat post that has a 20 mm setback I could use. The fitter I used suggested I go to a 140 mm stem and 46 handlebars.

Here's the test of core strength for the issue of too much pressure on hands. Riding along on the tops, drops, or brake hoods - the test is the same. Start with riding the tops = 'Can you take your hands off the bars and hold the forward leaning position?'. For how long? Riding brake hoods = Repeat. OK, skip the drops, but try a lower body position on the hoods and Repeat.

Every ride spend some time riding with no pressure on your hands. It's a physical training exercise that will greatly aid your bike handling skills. If i rode gripping the bars my hands would tremble and my bike wouldn't be nimble.

edit: bend your elbows more to allow them to be a shock absorber between hands/wrist and shoulder.

Beyond that, i hate to recommend to someone with recent significant injuries.
My old body is 6"1', 200#, with average proportions. I like a road bike with 58cm of top tube and 12cm stem. By traditional sizing standards, that translates to a 59/60cm frame. A 61/62/63cm frame usually fits too, but maybe 11cm stem. I like narrow bars 38cm, never understood the trend for wide ones on a roadie. 46 seems crazy wide! My guess is with saddle fully back (at KOPS) and 14cm of stem the frame is possibly too small for you. How many spacers to get the stem to a comfortable height? A larger frame gives a taller head tube.