i have just realized i'm an idiot!
when i joined the gym, i thought "ok, i'll lift light. 10 kilo plates should do it". but i had forgotten the weight of the oly bar and thought it was half of what it was.
and now, three gym sessions later, i realize that i had only been counting ONE of the 10kg weight plates. so i had started out again thinking i was lifting 20, then thinking i was lifting 30, when in fact i was lifting 40 all along. which explains why i got so frigging sore, but makes me go because it shows that my strength didn't go to waste as much as i thought