How Much Should I Eat?

Hey, everyone, I have a question for you smart folks :)

I am doing insanity 6x a week (ok, so I just started Monday lol). How much should I be eating? I calculated my tdee, but I never know whether or not I am eating the right amount of calories based off what I am actually burning. I burn about 400 calories each time I do it (per my polar ft 4). Here are my stats:

CW: 134
GW: 125
I am 5'4.

I have little to lose, so I am guessing I need to be losing about .5lbs a week. On my workout days, I am eating about 1500 calories. This seems low, and I am scared to increase it, but I don't want to crash and burn at some point either. That being said though, before I started insanity, I've been doing 1200-1300 calories on sedentary days and about 1500 on active days. I've only lost about 5lbs in the 3 months I've been serious about this. And I haven't seen any weight loss in the last month or so, but I have seen an inch drop off, so that is encouraging. Can someone give me some advice? How much should I increase by? I try to give myself some leeway just in case i'm not burning as much as I think, or if I am off on logging my foods. Any help would be helpful. Thanks :)