Not losing weight

As you are already a healthy weight, losing more is going to require you to eat a net amount of 1200 calories a day for weight loss. That's what I'm on and I'm 5'6" and 143lb, so considerably bigger than you! If you are accurately logging your food, you need to start counting exercise calories to make sure you are using as many calories as you think you are - it is incredibly easy to overestimate. Some apps unfortunately include resting calorie use and you end up double counting, so I go with the MFP figures. I like to eat about 1600 calories a day and for me, those extra 400 calories are earned with 4mile cycle to and from a 1 hour pilates class, or a 45 minute strenuous swim, or a 15 mile cycle. Given that I'm not perfect and have the odd day where I eat more, I'm losing weight steadily but at less than 1/2lb a week.

If that sounds about what you are doing, bear in mind also that you are already small, so even at 1200 calories you are going to lose weight pretty slowly, probably slower than 1/2lb a week or so - which is good, and healthy but frustrating if you are impatient - I so get that! But this rate of fat loss is really easily masked by non-fat weight fluctuations, so keep faith and be patient. You'll get there.

1200 was way too low for me at 5'5", 150-something pounds, age 59, while eating all exercise calories. (Got weak and fatigued.)

Believe MFP's calorie estimate, not some random person on the internet's calorie experience (including mine).

OP, it's early days yet. I think your exercise frenzy on start-up, and your injury, may've caused extra water weight retention, which could temporarily mask fat loss on the scale.

You may get a clearer picture by tightening up food logging if you aren't there yet (use a food scale), because precision is more important for many of us as we get closer to goal weight.

You need 4-6 weeks of experience to know the net result of a new regimen, and that's doubly true if you're premenopausal. Hang in there, be patient, and see where you are in another month.

Best wishes!

Just to reiterate.
Don’t start playing with your calorie intake so soon after starting. As @annpt77 said it is probably water retention from exercise, and maybe injury, that is masking your fat loss.

Give it a whole menstual cycle, this and ovulation cause water weight too, before altering everything.

0.5lbs a week is a good goal for your stats, so it will be slow.

If after a month you decide to change your calories to what MFP recommends, be sure to eat back exercise cals, use the MFP estimate. Your other option would be to use an off site TDEE calculator that includes exercise.

Cheers, h.