Was moving in with my girlfriend a mistake?

So back in October, I moved in with my girlfriend, to an entirely different city. I'm 19, she is 21. At the point we moved in, we were only dating a couple of months, but had been good friends for a couple of years. But lately, I am having second thoughts, kind of. Recently she had been extremely unpleasant for a week, before shark week, which I guess is understandable, but that's not the only thing. We dont talk as much as I would like to, for example on the bus home. But, my question is, did we make a mistake? How long should people be dating before moving in together?
Was moving in with my girlfriend a mistake?
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