Need help resetting my goals

Hello,
My first time writing and not sure I'm in the right area so apologies in advance.

I never thought this would come out of my mouth but I'm concerned I'm losing weight too fast. Overall I have about 80 pounds to lose and I want to do it the healthy way so I will keep it off this time! I'm not sure what area of my goals I need to change. Here are the details:

My set goal is to lose 1 1/2 pounds per week. Activity level is seditary and I log my weight monthly.

The reality is that I lost 15 pounds in the first month. Then I overate my weekly goal (during Easter Holiday) by 600 plus calories and still lost 3 pounds last week.

In regard to activity level, I have a desk job 5 days/wk and work retail on Sat/Sun. 4-5 hous no sitting. I log this under exercise ranging from 400-600 cal burned depending on the day.
. I do strength workouts 2x a week and 30 min cardio 2-3 days a week. So is sedentary the right level?

In terms of diet. I typically eat all my allowed calories except for the exercise. I like to bank some of those in case the machine is off or I want a splurge one day and go over my calories which I have. That said my days vary.

The problem is: after Easter I saw I had lost 3 pounds and so I ate a couple hundred more cal this past sat and saw a 1 pound gain on Sunday.

What area of my goal setting should I change so I lose at the right pace but without gaining weight? Note: reducing my exercise is not an desired option for me.

Please help! Any suggestions?