Hi R.,
I am sorry hear about your hair loss! It is unnerving, I know! Please see my post here:http://mamasource.com/request/8817944183756029953 (look for R. N.), since this information may help you. If you need more detailed information, you can email me a message via this site.
If you feel your regular doctor or OB aren't helping you, I would insist on seeing an endocronoglist, even if you don't think it is your thyroid, it could still be related to your endrocrine system.
Alternatively, you could pursue something like Chinese medicine, which could include acupunture and/or herbs. This kind of treatment can be very safe during pregnancy as it has been for thousands of years. They will consider your system as a whole and work to find your body's natural balance - since "symptoms" usually signify that things are out of balance.
Good luck!
R.