You will need to talk to her about having other partners because it seems unrealistic to expect that you would stop wanting to have other partners, and no, having a child would do absolutely nothing to stop your desire to have there partners because there is no magic. So you will just need to talk to her about your having other partners without necessarily leaving her.

So that is about the issue of other partners.

I do have a friend who is into self-sufficiency. You can combine self-sufficiency with having children and she even takes her twin daughters camping to Stone Age camps where they are taught self-sufficiency.

I do not know though how you would do that with a wheelchair-bound person.

You will find that self-sufficiency and anti-consumerisum coexist with polyamory quite happily so you should do well with having other female partners in an open fashion.

The questions about the back pain possibly getting worse from having a baby and the effects of back pain medication on the developing fetus and/or breastfed baby will all need to be answered by healthcare professionals and it seems that the first thing to do is to have these questioned answered in order to start accumulating the facts that would figure into your decision making process.

Good luck!