Trying not to co-sleeping

I need advice. I do NOT want to cosleep. I always start her off in her crib but when she wakes to feed in the night I always fall asleep while nursing her. I've resorted to feeding her laying on my side because I'm afraid I'll drop her while I'm holding her. This is how I ended up co-sleeping. Any suggestions on how I can get her back in her bassinet? What have you guys done to stop co-sleeping?

Some background information: She is 3 months old, born on time, and is perfectly healthy. Once she is asleep for the night she only wakes to feed and immediately falls back to sleep. I have gone back to work full time and I am an extremely light sleeper. I usually always wake up in the position I fell asleep in. We are breastfeeding and supplementing with formula as needed.