How soon after unprotected sex can you start to develop early pregnancy signs?

I only had sex two days ago but my breasts are really tender. It was unprotected and I am very nervous. I know that you have 72 hours to take plan B, so could i actually be pregnant after only two days when Im supposed to have 24 more hours to take a pill that stops and egg from properly fertilizing and implanting? Basically I just want to know if I could actually already be pregnant or maybe this is just pms and im freaking out for no reason.|||If you have unprotected sex it's ALWAYS possible to be pregnant. But you wouldn't develop signs til later. Like a month or two later. Some people never really have many signs. But if I were you, and if you don't want to have a baby, I'd take the plan B pill ASAP.|||Fertilization of egg in 2 days is biologically impossible. It takes a week or two and u get da signs after a abt a month. Having unprotected sex can result in pregnancy bt just in 2 days, its impossible!|||As far as actually being pregnant already? I think it takes a day or two so you could be..but no you wouldn't be able to tell yet.