Is it possible to downgrade to ios 4.3.3 without SHSH?
If you have your SHSH's saved for 4.3.3, then you should be able to get back to 4.3.3 with some help of TinyUmbrella (it also has a button to get out of recovery loop, maybe you can try that?)

If you don't have your SHSH's saved, there is no way you can get back to 4.3.3 (or any firmware version for which you didn't save your SHSH's, for that matter...)

Official download links are to the right of this page: http://thefirmwareumbrella.blogspot.com/