I've had false plus lines before so I'm not going to get wound up over it until I get a blood test confirming it.
Pregnancy.org has a nice pregnancy calendar. I was reading the last few entries with a conception date of May 18th.
May 26 -- Early pregnancy symptoms include sore breasts, cramping, mild nausea, fatigue, increased irritability, or sometimes you might not feel anything at all -- in which case you're blessed.
May 27 -- Morning sickness could set in. Your brain might not know your pregnant but your body sure does.
May 28 -- The blastocyst contacts the endometrium.
So things look interesting...