Yeshivishmom, In tzinues there is alot of extra things that you do because u feel right about it, which is why it is so hard to answer those people who say “where does it say…” Most of my friends wear short sleeves over long sleeves, it is not only a t-shirt look but they make very nice shabbos tops and suite jackets as well. I dont know in seminary I just felt something about it, I didnt feel like a bas melech, it is a look and I just didnt think I felt like malchus in it. So I gave away all my short sleeve tops, it is hard because most of the stores sell pretty things, but lifes all aobut struggle.
A teacher of mine told us she sees a bigger problem with slingbacks than high heels, so it all depends on you and how you feel about that matter. But always try to highten and raise your sensativities.