To answer your query specifically, yes, you may be pregnant. This is possible even in case of clamped tubes as the failure rate of a tubal ligation
is almost around 5%.
However, your symptoms are not very specific to pregnancy
. It may be PMS (PreMenstrual Syndrome
Drink adequate fluids; give rest to your back.
Meet a Primary care
physician at his office and get your blood pressure checked and a general physical examination will be better.
Hope this helps.
Get well soon.