Re: breastfeeding and birth control
Honestly, you can get pregnant even if you aren't giving a bottle. Breastfeeding alone isn't a reliable form of birth control, since your fertility can return at any time and you will ovulate before your period comes back and could get pregnant without ever knowing you are fertile. But skipping feedings does increase the likelihood of your fertility returning sooner.
Why do you feel like you can't keep up with her feedings? It could be she's been going through a growth spurt if her demand has increased suddenly. If you do give a bottle for now it would be best if you pump during that time so that your supply doesn't drop. Those first couple of months are the toughest, it seems like all you do is nurse and change diapers, but it does slow down and she will start to space her feedings out more and probably get a little more predictable. For most babies that starts to happen around 6-8 weeks old.
“We are not put on earth for ourselves, but are placed here for each other. If you are there always for others, then in time of need, someone will be there for you.”