Don't get me wrong, a good bridal dressmaker will know exactly how to go about making you a beautiful flamenco dress, given a few photos and the right material - but there's one place where she's almost guaranteed to get it wrong.
When you're dancing, you have to move your arms through a far wider range than you do in everyday life. Both times I've had dresses made by non-specialists, I've been unable to get my arms above my head!
The easy solution is to choose a sleeveless design, of course. Or choose a cape or puff style instead of the tight elbow length version.
You'll also reduce the problem by using a stretch fabric - if not for the whole dress, at least for the sleeves (for instance, you could have lace sleeves in the same color, made of stretch lace).
If you're determined to have tight sleeves in the same fabric as the dress, you'll need to allow more ease in the armpit area. If you have an existing dress that's too tight, you can achieve this by adding a diamond-shaped gusset.