Were you sexually active and had unprotected intercourse? When was the last time if so?
The nipple discharge is hormonal and unrelated to pregnancy (not a pregnancy symptom but more a symptom of hormones out of whack). Being late or having an irregular period could also be a symptom of having out of sort hormones. Not too uncommon even if it has never happened to you.
So, when was the last time you had sex? We'll start there.
That's a pretty good list of early pregnancy signs - fatigue, light "period", backache, nauseous?, weird cramps, headache. How about emotions, appetite, peeing, breast and nip signs, light headed and more? If you had sexual exposure a couple of weeks before your period was originally expected, a home pregnancy test would be the next step.