As zac pointed out, your posture is extremely poor.
But most importantly, WHY should photogs want to shoot you? What do you have that sets you apart from the everyday bugis ah lian/teenie girls? Are you tall? Or the regular, "Singapore size" girls of 154-160cm?
Your main asset would be your face. And in this regard, I find you decidedly average. You don't have the classic model features, nor do you have the looks that would make me take a second look at you if I passed you on the street. Instead, shooting you would be a real challenge in order to find an angle that actually flatters you.
You have a very "top heavy" face in that the top part of your face (bottom of nose up) looks disproportionately large comapred to the rest of your face. You have chipmunk cheeks, no definable cheekbones. Your mouth and chin are very small, which means your cheeks hide whatever jawline you may have.
Would I shoot you? Nope. Would I join a paid, organized shoot? Only if there were other models where I saw potential for nice pictures.
You're essentially a "plane jane" trying to be a model. Will you still find people who will shoot your for TFCD or even book you for a paid shoot? Sure. We see a LOT worse "models" on here all the time. Can you really make money off this or last in this field? No.
Sorry if that sounds too harsh; I'm just being bluntly honest. I'm sure you're a great person in real life and will find a man who will think you're the prettiest thing on earth.