Bathroom reno gone south

[codebreaker9000]

Hey everyone, I've been referencing old posts on this site a lot to help me do things correctly and it's been really helpful. Unfortunately I'm stuck.

In short, I started a bathroom renovation in our house, the toilet tough in is only 8" from the tub wall and everything felt smooshed together. I demolished everything down to studs and removed the tile and subfloor.

What I found were many cut joists and lots of water damage. I decided to update the old cast iron stack to pvc and so I cut it out.

Here's where words will make confusion so I'll try to let the pics do most of the talking.

Basically I can't figure out how to bring the plumbing back while staying in code while also having enough vertical space between the joists to fit my pipes and connections.

The vanity is on the left, the toilet in the middle, and the tub in an enclave to the far right. Oh yeah - there's also a joist smack dab on the 12.5" location for the rough in.

What's the proper way to hook all this up?

I'll include pics of the original layout for reference, as well as the view from under the bathroom

 

[Breplum]

you will likely need to reframe the joist that is in the way of the toilet with a doubled header. when double header is used you normally have to double up the joists on both sides, but in this case you have a wall to take one joists load.
you of course don't need a 4" drain, so reduce the WC to 3". Hire a plumber or buy the tools and stick with cast iron. The noise from plastic drainage flushing is less than nice.