How early can you experience pregnancy symptoms?

Im disgustingly regular on my period but now I'm 2 days late my boyfriend and I always use the withdrawal method any way I was told if he has previously ejaculated that sperm cld be in the precum.. I'm 22 and in college not really ready to discuss this with my parents bc I knw they'll be disappointed but I've been feeling nauseous all thru out the day I've been getting dizzy a lot and I have no appetite my body feels tired and sore like I just wanna rest I feel like my legs are abt to give out sometimes but this incident happened almost 2 wks ago isn't that too early to be having symptoms of pregnancy?