Pt 21yrs. 6 days of delay, first blood exam 3 days after missing period results negative, sensitivity on both breasts w. Liquid at squeeze?! pregnant?

Not likely. Since you had a negative blood test, it is very unlikely you are pregnant. However, if you are not currently nursing, you might consider seeing a physician for a full evaluation of your nipple discharge. And also repeat labs is symptoms continue.
Possibly. Repeat the pregnancy test at 7d, if still negative and symptoms persist make an appointment to see your physician.