I didn't realise I was PG for 2 months as I was seriously ill with an unrelated condition at the time (which took all of my attention away from my PG symptoms and missed periods). However, I did have a lot of symptoms (which I only realised in hindsight were PG-related). They included:
A sense of smell like a demented wolf/vampire. I could smell people before they arrived at my house, and couldnt go NEAR my husband's wardrobe (suddenly smelly), my study (suddenly smelly), anyone who'd ever smoked (suddently smelly), or lillies (used to be my fave smell but suddenly putrifyingly bad!)
Suddenly needing a wee whenever I left house (and sometimes weeing self in bookshops
.
Period-type pain (which I thought was PMT for 2 months - durrr).
Breasts so tender and swollen I thought I'd been clubbed round the chest (again I mistook this for PMT).
Nipples like agonising bullets.
Wretching all the time (but not actually being sick).
No periods (should've been a dead giveaway).
Demented cravings for citrus fruit (a whole bag of clementines a night).
Complete aversion to my previous vices (caffeine, nicotine, alcohol).
....yeah, so you think I would've twigged I was pregnant really, but no. When I found out at 8 weeks I actually fell off the loo in shock! 
And I'm a health professional!!!! 