Upping Calories-How much weight gain to expect?

I am new here and am struggling to learn how to diet in a healthy way after 2 months of dieting in an unhealthy manner averaging between 400-600 calories with a once a week 800-900 calorie day. I did my BMR and it is 1430 and my TDEE is 1716. I am 5'3 and 146lbs looking to drop 10 or 15 pounds. I realize I am way under on my calorie limit and would like to up it from 600 to 1,000 calories and a week later, from 1,000 calories to 1500 which I assume is a good settling place for weight loss? So for going from 600 calories to 1500 calories in 2 weeks, is it safe to assume I will gain weight even though 1 pound of fat is 3500 calories and I'm still at a deficit? I'm aware there may be some weight gain, but what I want to know is how much roughly to expect? Should I expect more than 5 pounds? I'm worried I will gain 10 or more. I want to do this right but am hesitant and don't have much support or anyone who will just help me lay out a plan of action. I feel guilty when I even eat 800 calories a day because I'm afraid I will ruin my progress of already losing 21 pounds. I have posted a few times today with only a handful of replies, please can someone help? Be kind to me, I'm trying to fix this while I am only 2 months into my unhealthy ways. I just need some support and guidance from those who have been there and done it. I have done thread searches for upping calories but nobody has said how much weight gain to expect or how long until my body adjusts and I begin losing.