If I'm at 7 points, and I conquer only one BF with Skyfall of Areion and Trinity Force equipped on my unit, do I win?

Yes, you win.

When you conquer that battlefield at 7 points, the standard point from conquering is replaced by drawing 2 cards (Rule 466.1.b.2 — you're one point from winning). But Skyfall of Areion makes Trinity Force's "When I hold" effect also trigger on conquer. That trigger goes on the Chain, resolves, and grants you the 8th point — and you win immediately upon reaching it.

The key distinction: the "must score both battlefields" restriction (Rule 466.1.b.2) only applies to the point gained directly from the conquer game action itself. Points from triggered abilities like Trinity Force bypass that restriction entirely (FAQ 7390, 8819, 10436).