After composing this post, I see now that
cameron_lansing is hard at work again dispensing expertise and wisdom to go along with it. I touched on a couple other points below, so I’ll go ahead and post this.
Saturday evening Masses after 4pm should use the proper readings for the Sunday. They don’t have to, but if they don’t, the Mass is not properly the Anticipated Mass for Sunday.
This is true, so far as I know.
Br. Rich SFO:
Many people misread the Canon that says that attendance at any Mass in any Catholic Rite on the Holy Day or the preceeding evening (vigil) satisfies the obligation.
This is true - some people misread it to include the phrase “except when the wrong readings are used.”

Br. Rich SFO:
No Eastern Rites that I know of have Vigils for Sunday or Holy Days.
I know that Maronites celebrate Vigil Mass for Sundays on Saturday evening, however for Pascha the Vigil may not begin until midnight.
Br Rich SFO:
The Document says that the proper readings must be used for the Vigil if they have their own proper Vigil readings or the Holy Day readings proper for the Holy Day on the preceeding evening. Sunday is a Holy Day of Obligation. The readings proper for that Sunday in whatever Rite you are attending should be used.
I don’t recall the documents which discuss wedding masses after 4pm, but I think it encourages exactly what you say - normal readings for the vigil rather than wedding-specific readings. However, it is a suggestion, not binding law. And regardless, it does not invalidate the mass attended by the OP, and thus Canon 1248 says she’s fulfilled her obligation.
I would also point out the example
Chatter163 gave, and which I’ve heard elsewhere in relation to other Holy Days: If there is more than one feast or solemnity on a given day, one or more masses celebrated may use the readings from the feast other than the Holy Day of Obligation. As long as you’ve participated on that day (or the previous evening), you’ve fulfilled your obligation. There is no need to call ahead to the church downtown near your office to find out what readings they’ll be using at the noon mass on such a double feast Holy Day.