Pregnant?

How soon after conceiving can you start to notice changes. I feel like I don't know my body as well as I should & I feel like I might have some symptoms but I don't know & its still soon to test 
-I've had some naseau 
-some light cramping a few days ago 
-much gasier than normal 
- frequent urination 
- somewhat heightened smell (this one im really unsure of )
-I've been eating more chocolate : I typically don't enjoy this 
 - I've also caught myself grabbing or holding onto my stomaching mindlessly 
I guess I just need some perspective. I feel like it's possible I could be but I'm also hoping to conceive so I'm worried it could all be in my head because I want it so badly. I had sex using the pull out method on the 25th of March so it'll be a couple more weeks before a test would show. How soon did you guys start noticing significant changes that you were expecting?