If she is getting enough nutrition (as shown by her growth) and you can stand to be her sole source of food, this is not a dire situation even though you will certainly want it to change soon. Is she not even remotely interested in eating food that you eat, even fruit or cooked vegetables? Usually by now, a child will reach for other foods and put them in her mouth. Is that not happening?
Do you bottles shaped like the nipple? Some bottles have much better nipple shapes than others. Have you tried them all?
I would get a consult from a breastfeeding specialist. Ask your child's doctor also for recommendations.
Okay------------ no child has loved breast feeding more than my second child. He wasn't growing well during his first month and they had me wake him up to eat. He quickly decided that he liked this routine and absolutely refused any type of bottle. He woke up frequently in the night as well because I had become his pacifier and snuggly. I was his comfort. While this was endearing for a bit after a while, Mama needed a break.
So, your daughter should be eating baby food and some cut up "big people" food by now. Are you saying she does not have this? To be honest, the nutrition of breast milk goes down significantly after 12 months and becomes more and more liquidy and just a drink. I'd get some vitamin drops.
So my questions are the same as AnnieBrooke's. Where is your child at with eating? This should be improving. My older son has sensory integration disorder and an issue with motor planning. He had trouble swallowing sometimes and then chewing. He gagged a lot and I had to be very careful. He'd gag and choke on a chereo. So, if your child is not eating------- there is probably an underlying reason why.
As to switching to regular milk from breast milk. Put a little strawberry or chocolate flavor in it. This is what I did for mine and he would drink it. Then you wean them down to less breast milk. Eventually maybe just do it at bedtime. Then ease that out. Going to formula is really not necessary as the point after 12 months is that they are eating. If your child is not eating, you will need to consult with your physician about how to meet the nutritional requirements.