Since 5 teams relegate from each league every season, it opens up an extra 4 spots for promotion into D2, on top of those teams that win their league. Those 4 teams are determined by order of record, with PD serving as the tiebreaker. You have the 5th best record in D3, so if any of the 4 teams ahead of you win their league (which seems highly probable), you'll be in D2 next season.
I wish I had your dilemma regarding extra millions. I don't think I stand a chance of staying in D2. My roster is poor - by D2 standards - and I have about a million dollars right now.