Some medical problems and hypothyroidism?

I am 19 and a female. I looked up hypothyroidism and I have a lot of the symptoms, but I have been tested before and it was negative.
I have very heavy periods. The heavy part lasts for like 2 days then it is very light, almost gone, for 3-4 days.
I have low blood pressure and I get dizzy easily. When I get dizzy I am unable to see and sometimes my arms and back start twitching and jerking.
I am always tired and I need more than 12 hours of sleep to be able to function.
I also have some depression and I am on medicine for ADHD.
What could cause these problems?

Professionals only please.

?2017-02-09T12:58:49Z

1

Mr E2015-10-09T01:45:42Z

often routine thyroid test results are wrong and fail to find problems which in fact exist. see an hio method chiropractor.