R.S.
This question is really a question only you can answer. I have been breastfeeding my son for almost two years. At four months, he stopped taking a bottle. I really only preferred breast milk, but if I wasn't home, my husband or friend could at least give him the formula. In the beginning, it really didn't make a difference except I started noticing that his tummy would bother him. I had many bags in the freezer but he wouldn't even take those. He only wanted fresh from the tap. Needless to say, there isn't any way that I could work. Like I said, he is almost two years old and I'm very tired. I wouldn't change a thing but I think working is to your advantage. I would try the formula as it is so important to get your rest. I really have to watch what I do. I wait to drive or cook sometimes because I just don't get enough sleep. For almost year, I was getting may be two hour intervals. It's a little better now but he doesn't sleep through the night.
I have been slowly weaning him for a year. I thought it was cruel to cut him off, but some mothers say it's the only way.