I'm going through a similar experience with my little guy right now. He's almost 7 months and I'm feeling like it's time to stop pumping. Fortunatly he's making it easy for me though by seeming to prefer his bottles (and spoons) to the breast these days.
Anyway, after talking to other moms that have made the transition one thing you don't always hear is that you should ween the baby over slowly. So as you're trying formulas instead of going to straight 100% formula in a bottle try switching at intervals. So at first make a bottle with 70% BM 30% forumula, then swtich to 50/50 then conintue to decrease the amount of breastmilk. It should help your baby adjust to the taste and ler her body get used to the formula also.
Another thing I learned from my lactation consultant is that the make up of breastmilk changes as the baby develops but obviously formula does not so the quantity of formula may be different than breastmilk. At night my son drinks 8 oz of formula before bed but there's no way he ever gets that much from my body in any one nursing session. You might see something similar as you make the transition.
I'm not sure about you but breastfeeding was very hard for me for a number of reasons. 4 months was my goal, then 6 and I'm still going at least a big. God for you for making it this far!