Breast and formula feeding

In the last couple of days I have started giving my LO one or two bottles of formula a day, otherwise he is breast fed. I’m finding breast feeding hard, he is stuck to me relentlessly and I can’t get anything done with my days. Then being stuck in the house really has an effect on my mood. My partner encouraged a couple of bottles of formula so that he could help. I feel guilty for giving my LO formula, like I’m depriving him of that time with me or like he knows I’ve had enough.

I might feel better if I know he’s at least getting some of my milk with the formula. How do I go about mixing the two?