Awwwwww
And loving Clark was the reason she was in a mess now.
Her hand smoothed over her flat mid-section.
Well, duh! It's squid-fic
As for where to go from there. The obvious choices are keeping them apart until Junior starts flying and invites them both to his or her wedding. Or, having Lois move back to Metropolis and Clark getting that other ring out of the drawer. So, the real question is what you could do to well-plotedly prolong their suffering. Having Clark think it's another man's child would only work by generating some reeeeealy big misunderstanding. There's always pregnancy complications. The most likely choice could be Lois coming to Metropolis, telling Clark and then getting into Lois-danger with close Superman proximity immediately thereafter, causing Clark to do the Clark-thing again.
Michael