Hi Researching, the more I read the more I think that poly would be wrong for you.
I don't think it is surprising at all that your libido is low with all those other concerms you have with people in your house and all the kids.
Here's a little snippet from my married life: after one of our children was born , many years back, my wife went through this and we had sex only about 4 times in one year (yes I was counting)
I was frustrated. But guess what? I didn't die. And we stayed married.