Yes the mind is a very powerful thing and many women (including myself) see all sorts of "symptoms" when they are TTC. Some women even have hysterical pregnancies, which is all controlled by the mind but they are not pregnant.

Last cycle in week 3 I had all sorts of symptoms including nausea, fatigue & breast changes & then they just went away. The funny thing was they went away right after I tested and got a BFN, so I'm pretty sure it was just my mind playing tricks on me.

When I was pg recently I did not have any symptoms before I entered week 5 other than tiredness.... things only kicked in after my AF was due.

I am now 6DPO and once again am experiencing all sorts of symptoms and am hoping it's not just another repeat of last month.

As for testing early, I read a post in here recently that it really is best to test after your AF is late. This would then stop you getting excited over a chemical pregnancy that you would not have even known about had you waited until after your AF was due. That said I know it is incredibly hard during the 2WW and I'm no longer that good at waiting either.

Of course, you could be pg and it's just too early to tell.... only time will tell.