Many years ago, I was also scared to go shopping for female clothes, initially pantyhose or stockings. However, I eventually got up enough courage to tell the clerk I was shopping for myself and found that made things a lot easier. The clerks tended to be very helpful. I'd even go to one store where there were three older women working. They couldn't do enough for me. They'd make suggestions and bring items to try to the change room. They even took a picture of me. There are also some stores, such as the one where I by my bras, that make a point of fitting men. In fact, clerks in that store have to be prepared to fit men, if they want to work there.
So, quit hiding and you'll find things go a lot easier.