1200 calories right for me?

Hi everyone,
I'm new here. Here's my brief history and stats...
I am 5'10", and very small boned. 5 years ago I was up to 153 lbs (now I know this would technically fall within norm healthy weight, but I am realllly small boned), and followed the WW plan and lost 33 lbs, down to 120 lbs. Looking back, I can see I went a bit far with the weight loss. Fast forward 5 years and since getting married last year, my weight is creeping back up and I need to nip it now and get back to where I am comfortable. My goal is 128. I started on Monday at 140.6 lbs, and have lost 2 lbs since then, so am now at 138.6. I'm sure a lot of that was retained water, because I have not been starving myself. Here's where I have questions - MFP says I should be eating 1200 cal/day. Does that sound right for someone with my stats, wanting to lose another 10.6 lbs? And if I eat less, will I lose quicker, or am I at risk of my body going into "starvation mode"? I have a trip 8/10 and would love to be almost there by then .
Lastly, I have put in my exercise, but MFP doesn't seem to be allowing me any additional calories for it. Still at 1,200 cal/day. I'm currently doing an ab challenge, so it's strength training, not cardio. But still, thought I would get more calories?

Thanks in advance for any insight!