I have to agree, the Playtex drop-ins and the Rubber/Latex nipples (as opposed to the clear silicone nipples) seemed to work best with several babes I nannied in the past, and with my youngest (who was not breast fed except for the first few days--long story).
When she's older, you may want to try again with a different bottle. My older daughter was not picky and took anything that was presented. My baby was picky at first, but now she's 6 months and will take silicone and latex nipples.
Make sure the formula or milk is nice and warm. Our oldest would take it cold, but our baby is SO picky! It seriously needs to be borderline hot for her to take it... Thankfully, she's starting table foods and is nowhere near as particular with that!
I also think you are WISE to be thinking ahead to January, even though other women here may not think so. Those next couple of months fly by, and your daughter will be much more adjusted if she's already used to a bottle by then. I wanted to be a breastfeeding M., but it didn't happen the way I would have liked--my girlies are formula kids and they are strong and healthy.
Also, GOOD FOR YOU, for going to school and raising two little ones! That's pretty amazing :)