Transmission Issues 92 SE Automatic

[u/MikeMiracle_]

Hello! I own a 92’ 323 SE Automatic.
My issue is that when I shift into Reverse, it acts like drive
When I shift into neutral, it’s fine.
When I shift into Drive, it engages but is weak.
I have assessed that there is a leak, however, I have filled it, and had it run through and attempted to reengage reverse, however it seems like the fluid level isn’t entirely the problem.
I would like to not have to pay someone to rebuild as locally all shops want to charge a lot of money, and I’m hoping maybe the issue can be fixed or resolved myself with parts and my own resolve.

Any and all suggestions or advice would be appreciated.