Hello fonetalker 101,
I faced the exact same problem with my Xperia E, I got stuck in a bootloop, and began to panick. So I know what demons you are facing
You can try a few options:
1. As mathewsj114 says you can try an older version of flashtool. And make sure that you have the Flashtool and Fastbootdrivers installed!
2. Install Sony Update Service. You can download it here: http://www.sonymobile.com/global-en/...pdate-service/
. Just install, run and select your phone model, then follow the instructions onscreen.
3. You said PC companion wasn't working? That's ashame!
4. If nothing works, try another computer!!! That's how I fixed my bootloop, my friend used Sony Update Service on his computer, and with him it worked! My personal experience is that SUS and Flashtool have some tiny bugs in Windows XP/Vista.
Hope I helped. Have a nice day and goodluck!