Hosed my fantasy football leagues schedule. How to fix?

I run a fantasy league on CBS with 12 teams - 4 divisions of three teams each.

I used a fantasy web site to create the weekly match ups so that each team plays each other team in their division twice and every other team once. A total of 13 weeks. It churned out the match ups, I entered them on CBS.

But…

6.5 weeks in, I notice that something is wrong. Somewhere I have screwed up. Some teams only have 3 divisional games, some have 2, playing instead, other teams from other divisions twice. That is wrong.

Now, we have played 6 weeks and no team has played the wrong team twice yet so somehow I think mathematically, the schedule can be fixed.

Is that a correct assumption? And if so, what do I do?

I have tried Excel, little bits of paper, big bits of paper, all manner of methods but it is simply too complex to do by hand.

Is there an way to fix this and get the remaining 7 weeks sorted out so that each team plays who they are supposed to play?

Thanks.