I been wondering if a blood pregnancy test could come back negative. And the person is indeed pregnant?

It's possible, but a blood test is pretty accurate.

If you think you're pregnant even after a negative pregnancy test wait until your next period is due, if you skip it than try another pregnancy test.

Yeah, its possible. Blood tests are much more accurate than a home kit, but can still give false negatives. It just depends on the amount of hormones it picks up in your body to be honest. But I reckon it should be pretty rare for it to be false... if you have doubts ask your doctor, he/she should know what's right, so if there isn't any other reason for your pregnancy symptoms wait a while and test again... however it is possible for it to be negative all the way through a pregnancy. But I'm sure you wouldn't miss the bump growing :)