[Jess~]

No it's not stupid at all for you to feel that way! I don't think feelings can ever really be "stupid", it's just the way you feel.
If you are this much in love with this design, do it. There might be people shaking their head while you're getting it done, but you'll be happy about it and that's all that matters. If anyone says anything afterwards, you can raise the blacked out arm at them and give them the finger lol.

It might help to write down your feelings and see if there are any other concerns you have besides being intimidated again. Maybe deep inside you could be doubting it yourself? Or at least wondering if they'd be right?
Just write how you feel and what you know to be true about this situation. I always find it helps a lot to remind myself what I know for a fact about a certain situation, it helps keep me in reality.

If you're scared to say what you want, write that down too. Sometimes when I go to the doctor I'm terrified I'll forget something I want to ask about, so I'll write it on a notecard and they've never said anything about me taking it out and reading it.
If you stay confident in yourself and your self expression, and show them that you are 100% sure this is what you want, hopefully they'll stop commenting about it and just do their job.