>>76257588
Could be

I lose a bit more than 9 lbs per month at 1500 calories a day being 6'1 so for someone 5'9 it could be a bit less like 7.

But the exact calculation doesn't matter because you say that you just started therefor you would lose water weight, around 5 lbs sounds right so you're not losing too fast then. You'll be able to calculate exactly how much of a calorie deficit you're at at the end of about 37 days, checking only the last month of it to not factor in any water weight lost.

Keep it up.