That’s your first mistake. Never wear anything anyone has bought for you - and shop by yourself so you can take as long as you need to in the fitting room.
When I try something on, I look at myself from every angle; I sit to see whether a skirt rides up or the waistband of the pants gap at the back; I twirl to see how the garment moves. It takes about 10 minutes per outfit to decide whether it’s flattering and well-made. You are the only one who has your own best interests at heart in the fitting room. No one else will spend that kind of time and effort on you but you.
One more thing: Although all of us can only afford to buy off the rack, tailoring does wonders. Nipping in the waist, moving a seam so it follows the curve of YOUR hips just so ... priceless.
I was just kidding. I have momjeans and tough, ugly Carhartts for the rugged work—chopping wood, cleaning stalls—when I am only going to be around women and I absolutely don’t care what I look like, because the important thing is to stay warm and get some work done. The little Old Navy jeans are for when I’m feeling and/or trying to be attractive, and am going to be wearing a tank top or some other piece of clothing suitable for women half my age. And they do look adorable.