My BPD ex's birthday was a couple weeks ago. Instead of contacting him, I wished a bunch of my friends a happy birthday. They knew why and thought it was pretty funny! I went out to an event that night, met up with friends, and had a great time. And I didn't get drunk or make out with anyone.
You have to make new memories during all of the tough times when you have sentimental memories about him. For four years, my memories of my ex's birthday were of spending it with him. Now my new memory is of spending it with friends and being happy. I suspect next year, I won't even remember his birthday.
Being a homebody is not pathetic. I love having some alone time, putting on the yoga pants, lighting candles, unwinding by myself, doing exciting things like filing paperwork while watching reality TV. However, while you're still recovering from the breakup, it IS good to keep really active with friends and family. And no, don't get drunk and make out with anyone! You don't need that. You're okay the way you are.
You can make it past 12 weeks. Aim for 24 weeks. And probably by then, you won't care very much anymore. Really.
If he was the initiator of getting back together with you, it will never change the dynamic. You will always find yourself under his thumb eventually. You can't win, and why would you want to exhaust yourself trying? Better to focus on yourself--get lots of sleep, excel at your new job, work out and look hot not for anyone but yourself,

! Enjoy your life. When you start to think of him, force yourself not to. It takes time and practice, but it will do the trick.