Help me please

Minnie
I'm so confused 😔 I'm 12 weeks and5 days pregnant ,I don't know if I'm still in my first trimester nor how many months I am ...and  every time I keep asking people they tell me oh you should know this stuff already if your having sex but this is my first pregnancy and I kind of don't know why me having sex how anything to do with my questions 😳😔