At 18-3, head-to-head would be:
UL 1-1
ND 1-1
USF 0-0
Not sure if that knocks us out (winning % of 0.500 does "beat" 0.000)
Record against common opponents (starting at the top) would be difficult to sort out given the uneven schedules.
The only teams ALL THREE schools played would be Nova and Pitt.
Versus Nova:
USF 3-0
UL 3-0
ND 2-1
Versus Pitt:
USF 3-0
ND 3-0
UL 2-0
(Not sure if 3-0 counts as an "advantage" over 2-0, tie-breaking procedures are not clear on this; with WBB, that only matters if all common-opponent records are otherwise "equal" and you have to start back at the top of the standings). From these, it would seem that ND is out based on their loss to Nova. Starting back with USF/UL, we have five common opponents: SU (both 2-1), Nova (both 3-0), Pitt (USF 3-0, UL 2-0), PC (USF 3-0, UL 2-0), SJU (USF 2-0, UL 3-0). As long as SJU finishes behind Pitt or PC, we might have the advantage. If 3-0 and 2-0 are viewed as equal, then it says "runs given up against each other." We didn't play each other, but that's the last line on the tie-breaking procedures. If you extrapolate to "runs given up in all conference games," we've already clinched (29 vs 35, with UL having games still to play). Otherwise, coin toss?
Right now, ND up 2-0 in the 5th, so it may not matter soon enough.