For a short tri you are probably better off just making a decsion about what to wear and then going with it for the duration of the event. You really won't have time to change/add clothing, especially in the transitions as you are already worried about wasting time.

If you really can't stand riding in a swimsuit (and you aren't lucky enough to find a great buy on a tri-suit) plain-ol' bike shorts and a (non-cotton)sports bra should do the trick.

My favorite pair of bike shorts for dus and tris are supper cheap and cheesy. In fact I would never wear them for "real" riding. Look for the opposite of what you want in good bike shorts: thin non-cottony fabric (dries quickly), and a really thin, amost non-existant chamois (think "pantyliner" vs. maxipad).

If transitions have you worried-- practice them. After your next swim (if it's warm enough) hop on your bike and ride, even if it's just around the block. Usually in a tri you will just put your shoes and helmet on and go. Don't waste time with gloves or socks. Hang your helmet on your bike handlebar, have your energy drink in a bottle on the bike and have your shoes on a towel placed next to the bike. During the bike drink drink drink. When you transition to the run just hop off the bike, toss the helmet and bike shoes on the towel, slip on your running shoes and go. Running stores carry "quick laces" which are elastic shoe laces so you don't have to mess with tying your shoes.

Have fun