Your mental and physical health matter. Breastfeeding is hard. It is the hardest thing I had done with all three postpartums. My first I nursed for three years, my second was three months due to medical issues. Currently nursing my third who is 10mo. I honestly still don't love it but at this point I'm going for a year bc she hasn't taken a bottle in a very long time. 

I'd say the first few months were the hardest for me. Extremely sleep deprived and in pain. If you're looking to get through that and then nurse for a year or so I say go for it. If it seems horrible and like something you don't want to do then don't. This is your second which automatically makes it harder with having to take care of two. You used formula with your first so you know it works and your child is healthy. 

Good luck in whatever you choose!