How many calories should I be consuming?

I am 5'7", weigh 200 lbs., female, 26 yo. I have been watching my diet and exercising for about two months now and have lost about 8 lbs. The thing is now that I have stepped up my exercise program, I am starting to feel a bit sluggish and my energy is down from when I started. I think it may be due to the fact that I am maybe not getting enough calories. I don't count them but I eat a lot of healthy foods, fruits, veggies, whole grains that sometimes aren't very high in calories.

If I do 45-60 minutes of cardio and strength training 5 days a week, how many calories should I consume in a day to give me enough energy and still lose weight? Also, how should I space the calories, ie more calories earlier in day or many small meals?

I know I should just listen to my body and I don't want to start counting calories obsessively. I just want to have a starting point. Thanks!