I know exactly how you feel.
I am 5'9" and you and I are probably about the same weight (I don't have a scale any longer). It does not help that most of the clothes out there are cut on the bias, made out of clingy fabrics and very "young" in style.
I used to own/operate a high end consignment shop that specialized in women's clothing. I helped a lot of women "transition" through several body stages in there life. I mean, our bodies are ALWAYS changing no matter what we do. We have youth, puberty, childbearing, middle age and senior years.... just as soon as a woman gets used to her body she gets to experience another change! It just ain't fair.
I have handled a lot of clothing in my life. Clothing is an important element in how a woman feels about her looks.
Here's the deal.... go to the mall either by yourself or with another friend who you can trust. Try on EVERYTHING and try on all kinds of sizes and don't let price dictate what you try on. Get to know what works and what does not work with your body. Get to understand how different manufacturers make their clothing. Get to know how to identify a quality made item vs a cheap trendy item.
Once you know what works on your body, you will have a better idea of what you will have better success with.
Most likely your boyfriend does not feel the same way you do about how you look in a piece of clothing. He loves you and he loves your body (men feel fortunate to have a woman they can trust). Women ALWAYS have body image issues.... keep that in mind. You do want to... you NEED to feel good in your clothing.
Give my method a try and good luck.