Hello, In_Love_…. – I agree your calculations. But let’s round the figures, to make it easier, as I’m sure there’s no need to count to the nearest single calorie.
Thus:
– Your recommended intake on non-fast days is just the straight TDEE figure – say, 1800cals per day
– The recommended intake for your fast days is, therefore, 25% of that – 450cals per day

Remember, you are not meant to be dieting on non-fast days. 1800cals is the correct intake to keep your metabolism** ticking-over at a rate appropriate for your given statistics and, if you ate to this level seven days a week, it would maintain your current weight. However, the sharp reduction, down to 450cals for the two, separate, fasting days, is enough to stress the body into various positive responses, including a safe, gradual weight-loss, but without causing any undesirable slowing of your metabolism (which would then make weight-loss more difficult).

The TDEE figure usually quoted for Ms Average is 2000cals and, if you thought your 1817cals was high, I tried another online calculator, for comparison, using your statistics, and that result was even higher- 1953cals!
Perhaps you should keep close enough to the nicely-rounded figures of 1800 and 450cals and see how you get on over several coming weeks. Hopefully, you will start to see the positive effects you wish for. Keep in mind that 5:2 is best seen as a relaxed but steady jog rather than a manic sprint – a new way of life rather than a quick-fix. The very best of wishes to you.

(** Put very simply, metabolism describes all those chemical processes whereby food is converted into energy to fuel the body’s daily activities, including the synthesis of essential nutrients from food to support the building, upkeep, and repair of body tissues, and efficient functioning of the body.)

My pleasure, In_Love-… – I hope everything goes well for you and you will keep contributing to the forum. All best wishes.