I never said nothing exists outside of me. Based on the evidence that minds are needed to describe what we see, then the external world can only exist in God's mind.
Which is practically meaningless. It makes no predictions about the world, it tells us nothing useful, and its only actual purpose is to reaffirm a belief that you have no evidence to support.
Atheists are in a pickle when they try to claim that things exist outside of our minds while relying only on their minds to say such a thing: CCR=Classic Circular Reasoning.
Your own reasoning (that the external world can only exist in God's mind) is fanciful and incoherent. You have no evidence to support such a contention, or even that such a being as 'God' exists in the first place. And saying that the external world can only exist in God's mind, because minds are needed to describe what we see, is incoherent. It is not a meaningful argument, because the fact that minds are needed to describe what we see has nothing to do with the external world being in a mind.
By comparison, the argument that there is a world external to us is supported by evidence - if I point at something, you can see me pointing at it. If you point at something, I can see you pointing at it. Furthermore, for it to be a circular argument, the conclusion must effectively contain the premise. You can certainly say that we rely on our minds in order to determine that things exist outside of our minds, but it goes no further than that. So your argument simply fails.