Mosca,
I would like to give you some psychological support.
Just don't let you be pushed down by people telling you to give up your dream. There is an increasing number of female pilots doing very well in cockpits. And try to see things from a different point of view: There are many shining diamonds in airline business, not only SIA.
Don't get me wrong, I don't want to minimize SIA but to put some emphasize on other possibilities. Once you stepped into business you may find a lot of attractive ways to work as a pilot.
And never put your aims below the level of possibilities which you still have. Just try and apply with SIA, and once they told you you are not tall enough - well, then try the next possibility, maybe Jetstar, which is surely a quite good choice to start with. But never say "... would be even enough for me". Try the first choice at first and then step to the next one. And I am sure you will find a place to make your dream come true. It might not always be as shiny as you expected right from the beginning but you will make your way if you want.
So, finish your university degree and then go ahead!