Two week wait....!!!

Ahhhhh I hate the two week wait!!!!!! Been TTC for well over a year now and I'm getting really impatient and really fed up! I think I had my first positive OPK stick on Sunday and we've BD'ed loads this last week or so... 
My question is; is there any way to tell if you've conceived before you get a positive HPT??? Or, can someone tell me, what is the earliest you can have symptoms?? And what are they??? Thanks :-) xx