Baby Name Poll

I posted a poll earlier but I didn’t get many replies and I really need some help in deciding. My first name isn’t desperately horrible or embarrassing but I’ve never liked it and it’s very difficult to pronounce and spell. I’ll be starting uni soon to do Portuguese and Spanish and I’ve found that it’s even harder for people who speak those languages, which all my lectures will, to say. I’ve always wanted to be Kate and if I want to change my name, doing it before uni would make sense. However, my problem is that my parents, especially my father, obviously love my name and I don’t want to upset them but I really want to go by Kate at uni. Do you think I could do that just by making Katharine my middle name (I can’t use my current middle because it’s my cousin’s name) and have everyone call me Kate or should I make Katharine my first name and use my current first name as my middle name? Just to clarify, I do want to make Katharine part of my legal name so that there is a clear reason for people to call me Kate. Thanks in advance!