I always wear a triangle inside + rectangle swimming trunk. Paiseh because swimming trunk too thin...

Haha, ya that's one of the problem too. I think I had bought a quite thin swimming trunk, a bit thin for me. It has liner, but when wear, I feel not comfortable. I feel like full naked in front of people. So wear 2 pieces always. Haha...

Actually you can breathe in and out through nose and mouth at the same time.

Erm...Actually breath in using mouth and exhale using nose is the appropriate way. That's why we have to learn "bubbles" before going to learn the breathing process in swimming process.

My swimming trunk a? Speedo one...

"Bubbles" is a underwater breathing process, to let the swimmer get used to breath underwater:) Basically just inhale in the air, but exhale beneath the water. It's used to be doing deep breathing for swimmer after swim.

Normally water won't go in after you exhale. Just maybe you're not used to it. Relax and just exhale normally and after exhale, just hold your breath. I used to have a very sensitive nose as well. No matter what I do I can't do front crawl. However after months of persistence, I managed to overcame it. Now if little bit of water entered thru my nose, it'll just come out from my mouth..if a whole chunk then teruk la...

Well, water generally won't go into your nose unless your nostrils are facing horizontal and upwards. Gravity. So, obviously, when you're doing a flip turn, it will happen unless you exhale through your nose.

In time you'll get stronger and will able to regulate the air exhaled. Perhaps you're not so used to it yet. Once yo swim for a couple of times or you have familiarised with the water, then you'll do better...

DOn't concentrate too much on exhaling until you miss the turn... when you start the turn, don't stop..  aim to complete in 1 go..

when you hesitate, that's when you slow down, then breathing will be difficult.. it will come to you eventually.