I'm bipolar2 also and 65yo. First diagnosed in 2009 so I have a long history of not being on medication. My symptoms are not as extreme as your wife's however. I have short naps but am never exhausted.
My psychiatrist in 2009 told my wife "you're greatest challenge is determining whether your issues are due to his bipolar or is personality". It turned out a great question because many argument she thought were due to bipolar later on were indeed personality. Therefore these issues were sorted through relationship counseling rather than medical intervention.
We cannot talk much about medication here except I can mention that the depressive side to my bipolar is managaed by a very mild anti depressant. Without this I'd frankly be a lot more depressed. I'm also on a mood stabiliser and realise it isnt the super fix all thing, it is significant but too much will make me feel I have no energy. This is an area that needs tweeking in some cases to have enough energy but still be effective to suppress mood swings. Suppress is the word because they wont be eliminated. Therefore a lot of tolerance is required on your behalf and other contacts.
Being a carer to a bipolar is a tough gig. After all "who cares for the carer"? The bipolar can be so wrapped up in their own struggles and if the carer in an "enabler" the bipolar person can become more dependent. The carers world becomes a world where they need support.
I would highly recommend a relationship counselor because I think your issues are more in the realm of tweeking time management than anything else. A toddler added to your lifestyle places a huge burden on both of you. Time out can include some very basic considerations, you'll find that simple changes and your partner being a little more considerate will work wonders.
That's why I used the word "tweeking".
I hope that helps. Repost if needed.