Is lower abdominal pressure and dull cramping normal at 12 weeks pregnant also i was confirmed by ultrasound but all my pregnancy test are negative is this normal as well?

What you are : describing, is likely not possible. Negative pregnancy tests, and viable pregnancy shown by ultrasound, do not fit together. A pregnancy loss, that has not passed as a miscarriage, will show a positive pregnancy tests for several weeks, as well. Possibly a bad batch tests could explain this. Blood pregnancy hormone levels, could be helpful.