what is the next step?

So I started counting calories to try and lose weight, I have also started exercising a little more, walking, stairs, martial arts. Here are my stats:

Female, Height: 5'3, SW: 262, CW: 254.6, GW: 150

I've been counting calories for about 6 weeks now, use the LoseIt app, which had me eating about 1700 calories a day, and ai lose all the weight within 3 weeks. For the past 3 weeks I have stalled out with my weight ranging between 254.2 at the lowest to 255.4, usually hanging out around 254.8.

I weigh all my food on a scale. I know exactly how much I am eating. Do I need to cut more calories to get past this plateau? I don't know where to go from here? I walk 30 flights for stairs a day, and do martial arts once a week for 2 hours (My Samsung Watch says I burn 1000 calories doing this), and I still am just hanging on for dear life at this weight. I just want to bust past it. Every calculator I have used says my TDEE is high enough where this should be a deficit.