Hi Helena, welcome!
The world is full of women who are your height and weight, so there is absolutely no reason why you couldn't look as much of a woman as they do. You say you want to avoid a trashy look, so this means no short skirts, no plunging necklines, not much skin showing, and conservative wig & makeup- all very obvious really.
Look at the world around you. Go and find a comfortable coffee shop and just watch what larger women wear. I'd say avoid bright colours and things that cling to your upper body. If you like a more formal officey look, consider trouser suits over a sensible blouse; if you want a more hippy look, go for layers of loose, floaty things and choose large items of jewelry.
Where you are so fortunate, and I am so jealous, is that your feet will fit many women's shoes, and this is where you could really experiment, if you can find shops that are ok with you trying things on. I'd advise you go for 50% comfort and 50% style. Never ever buy anything that is just a bit too tight, you will always regret it, even if you are totally in love with the item.
Without knowing more about what sort of clothes excite you, it's hard to give better advice.
I hope you have fun, please do let us know how it goes.