Being a member of Nursing Mothers Counsel, I can definitely disagree with Sara L.: everything affects your milk, the taste, the color, etc. Babies can taste what you eat in utero, and they can taste it in your breast milk. Affected babies are most likely to be sensitive to 4 things: chocolate, cruciferous veggies (broccoli, cauliflower, etc), citrus foods (oranges, lemons, juices, etc), and dairy (most often, milk). MOST babies don't have an issue with anything mom eats, especially when eaten in moderation. Caffeine also seems to affect some babies negatively, but again, moderation is key.
I can say this with confidence because my son absolutely could NOT have green peppers! I couldn't even eat sauces that had green peppers in it like sloppy joes. I had to read labels. He was also sensitive to the cow protein in milk, so I had to switch to Lactaid. Thankfully, he grew out of both sensitivities around 7mo. A friend of mine right now is nursing her 7mo, who is dairy and gluten allergic. She can't eat anything with certain ingredients.
However, your daughter's current behavior doesn't necessarily have anything to do with what you ate. Babies are born with an immature digestive system with many holes, and it isn't until around 6mo of age that all those holes are finally sealed. For now, there might be lots of gas, and that could be completely normal. It also has nothing to do with the nursing position.
The first thing I would look at is her latch. Does she open wide before she latches? Once on the breast, are her lips flanged out like a fish? Do you put nipple to nose to allow your nipple to point to the roof of her mouth? Once latched, do you see more of the top of the areola than the bottom signaling a correct asymmetric latch? Do you hear any clicking or smacking noises when she's at the breast? If you hear these types of noises, it likely means that she doesn't have an optimal latch.
Just some ideas, but if you'd like a personal counselor for free one-on-one counselor assistance, feel free to email off subject :)