I never really considered myself to be a "nature mommy". I always felt rather ambivalent about breastfeeding. I breastfed Charlotte and supplemented with formula from the time she was three days old, and I didn't feel an ounce of guilt.
However, with Kate, I was fortunate enough to be able to exclusively breastfeed her. It came easier, she wasn't quite as hungry, and it just seemed to work. Yet now, with going back to work and a variety of social functions to attend, I decided that it was time to supplement with some formula.
Of course, I didn't think that this would bother me at all. I have NOTHING against formula! In fact, I was always more offended by the lactation consultants than in favor of them...I felt pushed and pressured with my first baby. But now, as I knew my daughter was receiving her first half formula/half breastmilk bottle from our new, amazing babysitter, I felt really sad. I felt like I failed. :(
Yes, I know that this is silly. She is still going to be 90% breastfed...it's only for when I am out or can't pump enough. And who cares????? My Charlotte did very well with a formula/bfing mix.
When I came home today, I stared at my beautiful baby. She was sleeping peacefully. When she got hungry, I was so happy to just lay with her and breastfeed her. When she pooped successfully, I was thrilled. I think you just love your kids so much, you just want them to have the best thing, always. It's just defining that "best thing" for you and your family that's the hard part. There's never an easy answer. There's always guilt. There's always sacrifice. But, if you're lucky, there's always a lot of love too.
P.S. Similac Sensitive seems to be great! So far so good!