Maintenance calories and activity level? Help!

francesca_c123456789

Hey! I have been maintaining my weight now for about a month. When I started to maintain my exercise was a bit all over the place so I decided to put myself in as sendentary and MFP said I needed 1620 calories a day. Now though I am back on track with exercise and I run about 3 miles three days a week at about 6mph. Normally I burn between 250-300 calories. I also do light strength training three times a week with my own body weight; this normally takes about 25mins. I am a bit confused as to how many calories I should eat a day, so far I have been eating back about 150-200 calories on days I do cardio, is this too much? Also I am 18 years old, female, 120lbs and 5ft4. Any help would be appreciated! Thanks!