My daughter was very, very stubborn - even for a 4 month old when she started daycare. Even the ladies in the infant room said they had never seen a baby so stubborn - she wouldn't cry UNLESS they TRIED to FEED HER! I tried every bottle I could think of!
You have a couple of extra options I didn't have at the time. At Babies R Us they have a bottle that looks a lot like a breast called Tommee Tippee that I'd give a try. Also, try Playtex bottles - they offer a variety of nipples and in the end the bottle my daughter FINALLY took was the original Playtex bottles with the flat topped brown nipples. I did notice that the nipples are now round on top. I *think* what she liked about the nipples was that 1) They had a flexing in/out motion when she sucked on them and 2) they were softer and more flexible than any clear nipple I ever found. Hopefully the new Playtex round top nipples are still as flexible and provide the some in/out motion the flat topped ones did.
I ended up going to the daycare at lunch everyday to feed my daughter because she just refused to drink a bottle! Eventually I bought breast shields and forced her to nurse with those on my breast (which was a struggle for a while) but she finally caught on - after a lot of angry tears!
A few tips to help babies learn to take a bottle:
Try breast shields to get baby onto a bottle. The baby won't like it, but it can help them learn to take a bottle nipple.
Do NOT warm the bottle to the temperature that you would a normal bottle fed baby! Your breast milk is only "luke warm" so a bottle shouldn't be any different in temperature.
Make sure there is breast milk all over the nipple before they start to suck so they can taste it and smell it. Sometimes the "correct taste" will encourage them to try sucking on the nipple even if they don't like the way it feels.
IF you use any salve or lotion on your nipples and your baby is used to it, try putting the same thing on the bottle nipple.
I hope this helps you and I wish you luck!