breastfeeding help!!

Due to unfortunate circumstances i was not able to breast feed my daughter for a couple of weeks and had to give her a bottle. Since then however i have been trying to get her to be on the breast more and more. She is 3 months now and for the last month or so she had been doing well and had no more formula. I had to unfortunately return to work so she still gets bottles of breast milk when i cant be with her. Now when I am with her and able to breastfeed she will suck on one breast for a bit and drink but then pulls off and wont relatch. i know she is hungry and i try to burp her change her and do everything i can to make sure she is comfortable but even when i express milk into her mouth to get her to latch again she will not or if she doesn't she constantly pulls off and cries and fusses.... what can i do? i feel like such a failure and dont want to give a bottle every time she needs to eat... please anyone help?