My first baby was breastfed exclusively for 6 months. He has never had any formula. And had his first taste of regular cow's milk at around 18 months. He continues to nurse and will continue to do so until he is ready to wean. However, as I went back to work when he was about 3 months, he was fed expressed breastmilk (EBM) via the bottle while I was at work.
My second baby is now 3 months old and is also exclusively breastfed. I'm not returning to work for awhile, so there really hasn't been any need to introduce the bottle. The one time we had to do it was when my hubby and I went for our first date 2 1/2 months after the baby arrived. Baby didn't like it at all, and ingested only a tiny amount of EBM before falling asleep.
Somehow the knowledge that my baby didn't like the bottle gives me great pleasure. For some women, being able to give their baby a bottle represents freedom. Freedom to reclaim some part of their lives from the all consuming needs of the baby. While I dearly miss my pilates classes, I don't feel ready to give my baby up to the artificial feeder, and to the knowledge that I can be replaced! I suppose, having experienced mommy-hood once before, I am all too aware of how quickly my baby will grow and learn to separate from me. My time with the baby now is so precious. The pilates classes can wait. The bottles can wait.