Have you tried giving her a bottle in the morning? At 3 weeks, we tried a bottle of pumped milk for the first time in the evening and DD choked a little and then screamed and refused to take the bottle. The next morning when she was really hungry she was much more receptive and ended up drinking the whole 2 oz.
We went to church about an hour away the next day (to visit family) and I pumped in the car on the way and she ended up letting ME feed her from the bottle during church. We've only breast fed in the 4 days since, and she has had no "confusion" after the couple of small bottles.