Then, in BTTF2 Marty indeed does travel to the future from 1985. But he is not traveling back because it is his first foray into the future.
In BTTF3, Marty spends his time in the old west until the very end he travels back to 1985. Doc shows up and presumably went to the future, but its not shown.
What the fuck. We got ripped off, people.
