I currently have Mary Kary Full Coverage foundation Ivory 204 it is now just a touch light But my Rimmel London Lasting Finish warm ivory 102 is a bit too dark What should I get?

Sometimes you just can't find the perfect shade for you. Right now that's where you're at.

I think your real problem is the sun has darkened your skin--it's summer, that happens--and now your winter foundation isn't working for you. If I was doing your makeup I would put equal amounts of Mary Kay and Rimmel on something--a quart-size yogurt cup cap works well for this--and mix them together.