WHY is your family involved in the planning?
That makes zero sense to me, and is likely why you fiancee is absolutely enraged with you.
You both had a shared vision for the wedding, which your family threw a wrench in. I can understand your siblings not going due to children, but your mom not going? Mom was pitching a fit to get her way. That was a big, flashing "I'm not welcoming you to the family unless you bend to my will" slap to the face.
The compromise of continuing your Portugal plans and having a second, back home, reception should have been a good one. However, it seems like your family, and especially your mother, are now trying to get their foot in and "help" with the planning when really they just want their way. Your fiancee already feels like they hijacked and then ruined her wedding, surely you can see how she would not take kindly to them inserting themselves into her plans even more? Especially since it would seem like they were doing it all for their own benefit?
Why is your mother stomping on your boundaries? You've told her again and again and again not to talk about the wedding, yet she calls to talk about wedding stuff 3-4 times a week.
You say "even though my family has said sorry and that they would make it work" -- what does that mean?
By "make it work" does that mean they're going to Portugal now? Or that they're happy with the back home party and no ill feelings about missing the wedding? Or does it mean that they're butting in and making more demands in planning?
What did they do to apologize and how are they improve their relationship with your fiancee? You say you've explained the bad feelings--what have they done to make your life easier by fixing things? Have they tried becoming friendly with your fiancee, invited her to do things, or gotten to know her better? Or did they just say they understand as they kept doing all the stuff that makes her upset on purpose? Because again, you have told them many many times not to talk about the damn wedding. Yet that's all they do.
Honestly, both sides seem horrible. Your fiancee is like a miniature of your equally controlling mother. Your future wife hates your family, and absolutely will require you to go low or no contact unless and until they do the heavy lifting of fixing things with her. She won't lift a pinky for these people after this: it will have to be them. You family dislikes your future wife, and expects you to put her in her place and dance to their tune, while they make your life harder and horrible.
Maybe take a very long break from both, and only come back when you're ready to make and enforce very good boundaries with either side.