OP, I am very similar size/shape to you, though a touch shorter. Have slipped from a 16 to an 18 recently though I would like to do something about it, but not motivated right now.
I can look good in the right clothes/make up, but I can look dreadful.
Please take some of the advice on this thread.
You really do need a bra to give you more shape.
Cardigans look dreadful on me. Jackets much better. You say they pull, try a large one? Doesn't matter what size the label says.
Fitted dresses can look good, no cling, just a structured dress with its own shape than skims over mine.
My legs won't fit in skinny jeans but straight jeans are good. I can wear straight jeans from M&s and Wallis happily.
Sadly, expensive clothes look much better on me, nothing cheap, nothing polyester.
For tops: no sacks. Either slightly fitted or 'blouson' style look best, with scooped or v necks.
So a basic outfit of straight jeans, good boots, fitted top & jacket - you're away.
Has anything I've said grabbed you at all? Do you want links to actual possible clothes to try on? Do you have a waitrose nearby so you can click and collect armfuls of clothes and return those that don't work? Do you have some spare ££?
I don't wear foundation on a day to day basis, tinted moisturiser only. Plus a little blusher and a great mascara (ysl false effect) and rose tinted Vaseline on lips. To turn this into evening, I add grey liner along the top of the eyelid and a cheap rimmel antique rose coloured lipstick which really 'lifts' me.