Flashed ROM less internal storage

[The00Stranger]

I have a TMOUS HD2, nice phone, I've flashed a few roms, Energy and Kumar mostly. So, the new 2.13 rom came out, I flashed this, worked okay but it was slow so I did a hard reset. still a little slow, I did a hardware hard reset - [press volume up+volume down and power key]

When the phone rebooted it was very slow, got an error message about free space. I connected the phone to activesync, the internal storage showed like 100mb capacity. Normally on the HD2 internal storage is 688mb capactiy. I'm not talking free space, I'm talking available space, drive size - capacity.

I flashed back to Kumar 2.0 there was a change in internal storage size but it was like 200mb, still not 688 as it was before. I never tried flashing from sd card, ended up exchanging the phone.

Can someone help me understand this? How can flashing change the partition size?

When this happens is there a way to get back to normal?