there are a lot of formulas out there to figure this out and all they really do is give you a baseline to start from.
Since you just want to maintain, why not keep a food log of what you are currently eating, also monitor your body composition every week or two. If you're losing too much weight, eat more. if you're not losing enough, do more activity. if you are balanced... then you just found out your balance. and yes, it takes a while to find that out!
This will vary based on your exercise efforts and your diet, so don't go jumping into anything drastically different during your evaluation time.
when it's time to start shredding off some fat, start by doing more activity, sometimes this makes restricting calories unneeded.