First Signs of Pregnancy?

Kailey • 22. Mom. Boss lady. Experienced Vaper. Feminist. Smarty Pants. Pizza Lover. Loving Girlfriend.
My partner and I have had unprotected intercourse last week (it was my birthday 😊) and he finished inside me. We were both pretty loaded and sleepy, so I fell asleep before I got a chance to get up and pee. I took Plan B the following day, but some things have started to happen.
I've noticed that my breasts are sore, which could still be the aftermath of crazy birthday sex. I've felt more tired the last few days which isn't anything particularly noteworthy, as I have a spirited one year-old at home who wears me out. But the strangest thing is that yesterday and today I've noticed a thin, milky discharge that's been leaking from me steadily all day. This isn't something that would usually bother me, but it was enough that I had to wear a pantyliner to keep myself more comfortable. I'm worried that I may be pregnant again.
So my question to the mommies is: what were your first signs of pregnancy? What was the thing that made you really think you may be pregnant? Mine was swollen/tender breasts. Comment and share with us, I'd love to hear your stories!