can i be pregnant if the home test comes out negative?

my breast have been sore and hurt for over a month now, they feel bigger and heavier, I've had cramps, gained weight even though i was doing exercise, sometimes i feel moody, and my stomach feels hard, i already did 2 home tests and came out negative, i went to the clinic yesterday because i was worried about my breast hurting and the doctor said everything was ok, she said she was sure i was pregnant and did a test came out negative but she didnt believe it, she still thought i was pregnant so she did another test and it was still negative, but sometimes i feel weird things in my stomach and i only felt morning sickness twice? im confused i think i could be but the tests keep saying no.... so could it be possible???