I had sex a month ago and I have so many symptoms of pregnancy. I'm very intune with my body. Why did the hpt come up negative?

Check again. Most commercial preg tests are very sensitive, and if done correctly, accurate. If you think one is false, recheck. Two pregnancy tests that result in a negative= very confirmatory. At times, the first few days before a cycle start may like like pregnancy due to changing hormone levels. My advise, first recheck. The odds that two tests are both wrong is pretty low. If preg, they would show now.