Personally I went from BF to bottles with DS very early on. Using the Tommee Tippee wide 'Closer to Nature' types and they work for us. I stopped expressing when he was 6w. My supply was dwindling then, so I just let it go rather than send myself into a worried state trying to keep it up. I am now getting 7 hrs sleep overnight (he is now 9w). I am SO much happier not to be tethered to a breast pump, he is happy on formula, the MCH Nurse and Paediatrician are all happy as he is thriving. I have time and free hands to play with DD, and because of the decent sleep - I have been able to get out and about, take both babies for long pram walks etc. DH has also enjoyed being able to feed DS.
Whatever you choose, you will be ok and so will bubs.