First, welcome "back" to the boards! I find that every time I fall off the wagon and start back again, this is the first place I come. I enjoy using the support and accountability of 3FC to keep me going. And to share my struggle and triumphs with those who understand!
As to BMI and calories, for those of us who edge over "overweight" and into higher categories, those BMI calculators that tell you how much you need to eat each day for your weight are notoriously incorrect. What works at an overweight weight does not necessarily have a natural curve into high-BMI-land.
I started about where you are, and decided to begin with 2000 calories/day. It's a nice, round number, and I thought it would be fairly easy to hit that target (and I needed something easily accomplished to begin with as I adjusted my food choices within my target range). After a few weeks, I lowered it to 1800, because that's where I was most days. Now, three months into it, I've lowered it again to 1600. This is the level that I can comfortably keep to within my plan, without hunger or cravings. And I'm losing a steady 1-2 pounds a week.
As to motivation... I highly recommend two books --
The Four Day Win, and
The Beck Diet SOlution. They both work with just about any food/exercise plan, and they focus on HOW our minds work as we diet. It's about retraining your mind to feed good habits and to discourage and learn strategies to minimize the bad ones. They've made a WHOLE LOT of difference for me.
Other ideas I've seen around the board include committing to do this (whatever your plan is) for a whole year. No giving up after four or six months when motivation wanes and weight loss slows down (which is always the hardest part for me!). Others are very involved in daily accountability threads, or find encouragement in face-to-face groups like Weight Watchers.
Ultimately, you'll find what works for you. And we'll be here to help you through each step of it, if you need us!