How many calories should I be eating a day?

You've got a pretty good start going but I would suggest lowering your weekly weight loss goal to 1.5 pounds per week.

Here is a great guideline for setting weekly weight loss goals:
If you have 75+ lbs to lose 2 lbs/week is ideal,
If you have 40-75 lbs to lose 1.5 lbs/week is ideal,
If you have 25-40 lbs to lose 1 lbs/week is ideal,
If you have 15 -25 lbs to lose 0.5 to 1.0 lbs/week is ideal, and
If you have less than 15 lbs to lose 0.5 lbs/week is ideal.

Hello. I'm currently tracking my calories on MFP app and to lose 2lbs a week it's telling me to eat 1270 calories a day. I tend to burn 400 approx with exercise & tend you use these calories too. So in total I'm having around 1700 cals. Is this healthy or should I be having more/less?? TIA x

11-12 x Bodyweight (lbs) is a good starting point, regardless of activity level - never "eat back" calories burned that is a flawed model of weight loss.

11-12 x Bodyweight (lbs) is a good starting point, regardless of activity level - never "eat back" calories burned that is a flawed model of weight loss.

MFP set me at 1200 cals a day and advised I eat back exercise calories. I always eat back my exercise calories and have been consistently losing weight since I started using MFP three months ago. If I didn't do this I would not have the energy to stay active. I've lost 15lbs which is an average of about 1.25 lbs a week...but I didn't have much weight to lose so I expected it to be around this number.

That's because 1200 is too few calories... do you really think 90% of people who want to lose weight have to eat this magical number?? Nope.

If you had set your calories higher (i.e. yourself) then you would not have to even worry about logging exercise.

I promise you that almost anybody can lose weight at 1700 cal/day with or without exercise. Exercise should focus on maintaining muscle mass and dropping fat - the "eat back" model will never accomplish this.