"Discretion is the better part of valor."
You don't want to run to far out in front of where your transition is, least you have a bad experience that shakes your confidence.
But you seem to have a handle on things, that is a cute cross-over shirt that is subtly feminine. There are other little things that you can do like adding accessories like watches, bracelets or necklaces that most won't notice but will be a change and reminder to you that you are pretty. Oh and also, instead of plain ol' tee shirts, try tank tops. Most will see "wife beater" (is that an Americanism?), but they feel different, feminine, without being as obvious as an actual camisole or bra.