Are you in an area with a university? Students often have some regularly scheduled time during weekdays when they can be available, the cost is often lower because they're willing to give up a little money in order to gain some flexibility with scheduluing, and if you get someone who is interested in a subject that your daughter loves, you can get some educational time out of the deal as well. It's also nice to have the help at your home. Then you could work with your daughter while the sitter watched your son, or you could just get out of the house and have some time to yourself if you need it.
I'd start there if possible.
Take care of yourself. Remember the advice from an airplane: put the oxygen mask on yourself before you try to help others. It's a great analogy for parenting, especially when homeschooling!
