Do some weddings actually take place during the “normal Saturday evening parish Mass?” Nice thought, but I’ve never encountered it (not to say it doesn’t happen.)
However, the OP is more concerned with his particular situation; he is fine, according to every reference I have found. The following is typical, from the Diocese of Davenport:
**A NOTE ON THE OBLIGATION TO ASSIST AT MASS ON SUNDAYS AND HOLY DAYS **
"The obligation to attend Mass
applies to the day, not the Mass being celebrated or the texts used. (emphasis mine.) For Sundays and Solemnities, the liturgical day runs from 4:00 p.m. of the calendar day before to midnight of the day itself – a period of 32 hours.
For example, on a weekend when Ritual Masses are allowed,
attendance at a Wedding Mass after 4pm on Saturday would fulfill the Sunday obligation. Likewise, if a parish celebrated the Ritual Mass of Confirmation on Sunday, the obligation would be fulfilled."
Here’s another link:
rpinet.com/ml/2507bi2.html
This same question has been addressed in the “Ask an Apologist” forum on these boards.
OP, I think you will find that you’re OK (up there in Massachusetts, my home state!)
God bless!