Wa alaikum assalaam Princess,
I am curious... what have you been wearing till now? And what kind of skirt do you want to wear?
Generally speaking, if your clothes cover you decently then they should be ok. Some women wear long skirts and long-sleeved shirts, some women wear loose pants and long tunics, some women wear long loose dresses, some women wear pants with a shorter skirt over and a long-sleeved shirt... there various different ways of dressing that are modest. And there are different needs depending on where you are. If I were in a very hot, dry country like Saudi Arabia, I would wear the long, flowing one-piece robes they tend to wear there. If I was in a hot mosquito haven, like Karachi, Pakistan, I would wear the shalwa kameez they tend to wear there. If I was in the capital region of Canada in summer, I might wear a long skirt and long shirt in silk or linen (if I can find them for a good price- thrift shops are wonderful!)... whatever is available, affordable, suited to the climate and modest.
(smile) And what is modest? (smile) It's what tends to mute the sexual attractiveness of your body.
On another point... (gently) Princess, I understand you are bursting with the wish to have your freedom... but please be easy on your father. Perhaps it is good for him to learn to let go a bit... but as a mother of adult children, I can tell you that it is not easy to see your children doing things that you worry are not good for them. (mildly) I have the feeling that you and your father have some things in common... if you can learn to be gentle with his flaws, then perhaps you will be able to instill such gentleness in your own children one day, for your flaws...
May God, the Kind, Help us to be good to one another.