DO NOT COMMIT TO ANYTHING
Honestly you really don't know what the birth is going to be like, what your emotions and hormones are going to be like and what your baby is going to be like.
When pregnant with DC1 I was so naive and thought I would have 3-6 months off and I made loads of commitments for work - full day meetings every 4 weeks, & I completed a PHD application at home in the first 16 weeks of DS life (often doing the drafts in the early hours of the morning) and it was just daft - it left me exhausted. I breastfed, like you i wasn't massively fussed about bf, but DS had other ideas and was a bottle refuser!, It was an absolute nightmare - when I had to attend full day meetings I ended up having to wean early just so he could have something when I wasn't there.
I ended up having 11 months off in total - there was a point at about 4 month when I was ripping my hair out and really wanted to get back to work but I think I was just exhausted and I think actually going back to work then would have been a nightmare and would have spun me into PND.
In the end I tried to stretch it out as far as I could - the last few months were by far the best as the baby start to become much more interactive and fun.
I'm now pregnant with DC2 and going to take 10 months at least (9 months & holiday) and saving now to try and take a full year. I'm only going back part time, I'm currently full time and I find it a killer.
I'm the main breadwinner and my work is important to me but it will only be a few years of part time and then I can ratchet it back up again.
Please do not commit to anything - I cannot reiterate it enough!