Tamsyn looks trendy and kre8iv to me, for the reasons
Siri said. Also,
Tamsin is a contraction of
Thomasina, which doesn't have a Y in it anyway.
But I like
Tamsin, it's unusual without being outrageous. It's also similar to the ever-popular
-son names for girls, but doesn't have the etymological unsuitability of the "son of X" meaning. The only drawback I can think of is that the ending is "sin", and the name kind of looks like "
Tam's sin".
Tammy's a good nn, though it's rather bland and dated to the '50s-'80s.
Miranda
Proud adopter of 15 punctuation marks; see my profile for their names.