Caloric intake now that I exercise

So I don't know if this is the best forum to post this in but I'll give it a try.  In the past month or so, I have begun working out more frequently and doing longer weight training sessions.  I am now working out 3-4 times a week alternating between:

- doing 20-25 minutes on the elliptical (medium resistance, about 5 miles/hour) followed by 40 minutes of weights (using free weights and machines) and abs on a program a personal trainer gave me. 

- doing 35ish minutes on the elliptical + 20 minutes of ab/core work

My main question is: how many calories should I be eating daily? Should I eat more on workout days? I am asking for guidance as I am having trouble figuring out what to plug in as my activity level.  A little history about me, I am 19 and have struggled with anorexia for going on 4 years now. I am doing better now, with my weight re-approaching a healthy level (I was in India for a month and inadvertently lost about 8 pounds).  I have managed to gain most of the weight as muscle since I began working out which has done LOADS for my confidence.  I am 5'3 and currently weigh about 104-105. Last year at this time, I was maintaining a weight of 99 at the same caloric intake, but with less exercise and over the past year at uni, I ate about 1200/1400 calories a day (BAD! I know) and my weight increased up to my highest weight (about 108) so I think I may have slowed my metabolism a bit, unfortunately.  I now eat about 1500 calories a day and other than my daily treat of frozen yogurt and a deep love of strong coffee, I tend to eat pretty healthily.  

Thanks!

Typically a reasonably active adult woman (over 21) should be able to maintain her weight on about 2000 cals a day.   If you're working out regularly and you're younger than 21 your energy needs are going to be greater.... 2200-2500 depending on how vigorous your workouts are.  1500 is far too low..

If you find you gain weight on 2200-2500 then it is very likely that your current weight is too low and isn't your 'natural healthy weight'.....  Strictly speaking, if you're in recovery from anorexia you should be aiming for a minimum BMI of 20 anway - and that's about 115lbs in your case.

Good luck

wow...i didn't think it would be that big of a discrepancy! I'm not quite sure where my weight will eventually settle, my entire family is very petite so probably around 105-110. Guess I'll wait and see.

Thanks for the advice - muchly appreciated