Right A you deserve to dress and feel stylish and pretty no matter your size girl !
While trying to lose weight, never pass on buying a piece of clothing you like and that fits you just as you are now. Especially if you have a lot of extra weight, that can take quite some time to slim down, so if you have the money, treat yourself and feel good now !
Women of any size should never trade comfort for style. There are many clothes that look pretty but are horribly uncomfortable to wear ( and there are a lot of comfy clothes that look like old pajamas, that's not what we want either 
). Only buy clothing you feel you could wear all day.
Since you're mostly wearing dark shades, maybe find yourself a few block color pieces that aren't too much out there but still vibrant. I find plain colors easier to wear and assort than patterns and more elegant but that's me ! Deep forest green, camel, rusty orange, bright red... whatever !
I have a bright red wool coat. It's a bold choice but I get tons of compliments on it every winter season. It's warm too. It's a stand out piece that about anybody can rock yet few people do it. Works great with grey or white hair !
When it comes to looking put together, I think nothing spoils a look like ragged out shoes. Wear heels if you're into heels, sneakers if you're into sneakers, but they should be clean and in good condition. Simpler = better. I like ankle cut leather boots because I think they're easy to match with different outfits.
I'm not overweight myself so my advice on cuts and shapes that fit plus sized figures is kind of moot, but I would avoid extra frills on the neck line that tend to accentuate breast size, they're more for flat chested women imo.
Keep in mind there is a good second hand market for plus size clothes as they're typically more expensive in stores. If you treat your clothes well you can get good money reselling them.