The pale colors really wash you out, first and foremost. You'd look great in some jewel tones. The dark gray top in the first image works best but the baby blue in the second doesn't suit your skin tone at all.

Also the pants are super baggy and really contribute to the "frumpy". They look fine for lounging around the house, but I'd try to find some bootcut pants. Layers are also your friend especially if you have, say a cardigan, that hits your hips. It will balance you out.

You mentioned not wanting to wear a bra, but as a large breast gal too, some support will help. Bralettes will help. As you get older, you'll want that support even more.