Natty.. i think good on you for making a choice! BFing isnt for everyone and you did well i think to get that far. I only made it 9 days with Jesse and decided that was enough. My nipples were cracked, bleeding and sore.. i did my best i felt. He is not any less better off in my eyes... considering his nickname is "smiley"!

Which formula have you tried her on? There are some that are quite stinky and some babies dont like them. Maybe also the type of teat you are using? I use the avent ones as they are larger.. maybe that might be an idea too, trying to get something that resembles your boob mostly.. i know Tommee Tippee do a version too.
Only thing i can also think of, dont know if it will work, it maybe after youve given her a quick drink from your breast, while she's hungry and gulping, then switch over to the bottle of formula? If you can express a little, that might work too, give her that from the bottle, then give her the formula, so she firstly learns to use the bottle and will take the formula next.

You'll get there.. and just remember you are doing the right thing as its what suits you and your DD.. thats all that matters.

Best of luck hun.