I never eat back cals burned through exercise. However, I will drink a protein shake, have a banana, or something after I work out if I'm hungry, or feel I need it. That would be totally different if I"m running marathons, or working out for 2-3 hours a day, but as it stands, I count my work outs as a bonus calorie burn
I wear a polar F6 heart rate monitor that calculates what I burn based on my HR, age, & Height (it has a chest strap). I even wear it to mow the lawn!! The PP gave a good site that can help you estimate if you want one. You can also use like Fitday, or any other calorie counter site has estimates (that are probably on the high end of estimating)
How many calories a day are you eating? I highly doubt you're in starvation mode unless you've been eating like 600 cals a day for months

It's just hard to drop the lbs when we don't have much to lose. My husband always tells me "if you want to lose a few lbs a week, just gain 120 lbs, and then you'll lose it fast like everyone else"