How did you know you were PG?

[Ponyup]

Background: I've been on the pill for 8 years; well about 2 weeks ago while taking my pill I got to laughing & might have spit it out, but we couldn't find it so I figure I did take it. But now I'm wondering if maybe I didn't get it taken & i'm PG now. My period just ended a week ago & i've been feeling off. Headaches, body aches & fatigue. Also I noticed last night that my boobs were bigger than normal & very firm. I tend to be paranoid & narrotic, so I was just wondering how soon you knew you might be pregnant & what were the early signs?

My husband & I are still not sure we want children. If I am pregnant it won't be a big problem just unexpected.