I get dizzy now and then too and I'm 18 weeks. Usually I get an attack of the dizzies when I'm hanging out washing, I think it could be from standing in the heat for too long maybe, I get dizzy if I don't drink or eat for too long or if I'm very busy for a long time without resting.
Just be aware of what your body is telling you and look after yourself, you sound as normal as the rest of us....