I'm going to agree that it's an overreaction with one caveat...

Are you two, for example, conservative or otherwise very much not the type of people who would have any kind of body modification? Is this something that goes totally against your societal norm? If so, (and forgive me for a kind of lame example, but I'm illustrating, here) I feel like it may be a Miley Cyrus/Liam Hemsworth situation when Miley was breaking her Hannah Montana mold. Liam fell in love with one person, and she morphed into another. I'm totally of the "your body, your choice" camp, but be aware that this may be your fiance's POV. One more thing: piercings can be expensive (I used to have a few, and because I went to a good shop, they weren't cheap). Whose money did you spend? If you're taking from the joint account to do these things, that may warrant a discussion.

That said, if you absolutely do not feel that this is the situation, then I agree with Christina; the two of you should sit down and have a discussion about boundaries and who makes the choices when it comes to each other's bodies. You have propriety over your body, period. Contrary to some beliefs, marriage doesn't change that.