Default TCL S720T flashed and internal storage is lost

I bought a TCL S720T from China about two weeks ago. It has 4.2.2 with 1GB RAM and 8GB ROM and is based on MT6592. When I first got the phone, the internal storage was displayed as about 5.9GB out of which most (about 5.85GB) was available. I would like to mention here that when I connected my phone to the PC thru a USB cable, the total internal storage was also shown as 5.9GB on PC.

I did the following to the phone and now I am in trouble... plz help

As I bought it from China, it did not have Google apps. I rooted the phone to get these installed. During rooting I deleted some useful original apps.

I tried to restore the phone to factory settings but the deleted apps did not return (I do not know what did I do wrong). I started to search for phone's stock ROM but could not find it. Also all information on the web is in Chinese and that too no accessible from where I live.

After a couple of days, I found a ROM on "lewaos" website. It was translated from Chinese to "S720T Le Frog bottom package. Zip" and the website claimed that it was the original ROM. I thought that it is the actual ROM by TCL so I flashed it using SP_Flash_Tool_v5.1343.01. When the system rebooted, the radio was not working as the baseband was missing, however, the total internal storage was shown as about 4.90GB. I just want to mention here that I never backed up my original ROM (bad on my part).

There was another ROM update given on the same website for installation using external SD card. So, I installed the ROM, but this time the total internal storage wasshown as 1.09GB out of which 1GB was available. I got worried and tried to find other ROMs to fix the issue. I found some ROMs from website named "needrom" and tried them too. Whenever I use flash tool to load the ROM which I got from LEWA website, the phone shows 4.9GB internal storage but the phone radio does not work. However, as soon as I install any ROM using SD card, the internal storage is shown close to 1.1GB. I have even downloaded the official ROM update from "tclmobile" website and installed it using SD card, but the internal storage is still shown as 1.1GB. Also, whenever I connect my phone to PC thru the USB cable, the total internal storage is shown as 1.1GB out of which about 1GB is free.

While installing ROM thru SD card, I have always adopted the process of wiping the factory settings and cache in the recovery mode.

I would also like to mention here that during the process of loading ROMs, I lost the radio operation due to invalid IMEI, which I later restored using AT+... commands (thanks to xda-developer forums).

Having said all that let me summarize my problems:-

I have lost the original Stock ROM of my phone and no support is available outside China.
Whenever I install ROMs through SD card, the internal storage is 1.1GB, I want my actual internal storage ie 5.9GB back.

Please help me to fix my phone

Thanks