I'm going back after 12 weeks too. I have a pretty nice situation though. My mom and MIL take turns watching my kiddos. It makes me sad, but there's an end in sight. I'm a teacher, so I only have to get thru 9 weeks before summer break. But by the time August rolls around I'll be a wreck. 180 days seems like forever at that point.
Try asking around to other working mamas in your area and see what they do. Or maybe there's an empty-nester in your area that would love to take care of your baby. I know with women especially (like my mom!), once their children move away, they sometimes feel lost. Watching your new baby might be just what they need.
I do have a suggestion once you do find someone. This will sound totally anal, but I keep a notebook for my mom and MIL. In the front of it has all the emergency numbers and directions for administering infant CPR. Then there is a page that has some negotiable items (like naptimes and mealtimes) and non-negotiable items (like back-to-sleep for babies). Not that they will read thru this everyday, but maybe by talking about it, and seeing it in writing, they will remember it. I also put a list of where everything they might need is located in our house. And the last section in the notebook are a stack of pages, and they fill out one everyday. I got this idea from a daycare. It has a space for them to write when they napped, what they ate, their wet/poopy diapers, and a blank section for them to put any notes. It might sound silly to make them fill that out, but it helps me keep up with how much milk I need to be sure to pump, and clues me in when they haven't pooped for several day, things like that. They didn't mind filling it out, and they would write little notes in it, like "walked to the park" or "collected pinecones", which I thought was really sweet and I could talk to my DS about when I got home.