Should I be lower than 1000 cals?

160cm, keep fluctuating between 67 - 70 KG month to month. I’m unable to fit a lot of movement into my schedule, so my lifestyle is extremely sedentary. It’s wake, eat, work, sleep, repeat. I think at the moment I’m averaging 1500 cals a day. Except i’m noticing more weight gain. Should I scale back to 1000 only? Or less? 900?

TDEE says my maintenance is 1600, BMI is 1390.