So stop the IF, and increase your calories and carbs!

If you are young & active & fit, there is no need to limit carbs or calories.

You probably jacked up your cortisol (from the IF) and are retaining some water (due to low calories.)

Go back to what was working & you will probably see the belly fat drop off.

"I just want to be fit/strong" & "I am not that active".

You have to align your efforts and your goals!

You're probably over doing it. IF isn't supposed to be chronic, don't do it every day (if you are). YMMV and all that, but I found out the hard way that doing IF every day leads to loads of cortisol.

I eat from 12pm (sometimes 3pm) to 8-9pm on IF days. I make sure to do IF on the days that I work out, but I make sure after a heavy work out, I skip the IF the next day and sometimes the day after. Also I don't eat for an hour after a work out, so as to allow for autophagy, not just insulin resistance.

If the work out was a heavy one, I do eat some carbs, usually half a sweet potato or banana with the PWO meal - if you do a heavy work out and feel like a zombie until the next day, eat some carbs after the work out. (And of course enough protein from good meat/fish sources for the next few meals to ensure muscle rebuild/repair.) I generally don't eat more carbs during the week than that.

I do sometimes work out while not IF'ing, but depends on energy levels. Since I'm also doing the cold therapy thing, if I actually feel the cold, I do eat, since that means I've not liberated enough energy from fat stores, but this is just a 4 rashers of bacon + 4 eggs breakfast.

At some point you just can't get enough calories out of fat stores and your metabolism slows down to prevent starvation, if you're also doing VLC, cortisol kicks in so as to provide enough glycogen, but this process is slow and if you're not eating enough protein (from your post, you are, so no worries), it would catabolize muscle instead, which gets to be dangerous, since it can take it from your heart as well.

Point is, listen to your body's symptoms. Once you're adapted to VLC, if you feel cold, or hungry, or lethargic, cut back on the IF. If you don't have a lot of energy, enough to complete your work out, go easier, or eat more.

(I say once you're adapted to VLC, because for those just starting out - not you, necessarily, carb cravings will cause unnecessary hunger, so those signals aren't reliable. This is due to high insulin levels preventing fat from exiting fat cells, but blood glucose levels gone low since carbs were also shunted to fat cells from the previous insulin spike, so you'd feel hunger anyway.)