It's a common misconception that fashion designers must be good artists. Especially with the internet as a resource, there are lots of creative shortcuts. Even the worst artist can learn how to draw clothes.
One of these design shortcuts is called a "croqui." A croqui is an outline of a naked person used by fashion designers to sketch their clothing ideas onto. There are croquis for essentially every type of human body: male models, female models, petite, plus-size, child, baby, etc.
The definition of croquis is French and means "lifesaver." Fashion croquis can literally save a wannabe designer when he or she doesn't have the drawing skills to keep up with the professionals. There are free croquis available with just a quick search on Google images.
If you want to turn your sketches up a notch, then there are special croquis to do that too. You can learn how to draw clothes in a more realistic way, using model croquis that show the lay and twist of the fabric and the human-like bends of the body. These are the same type of fashion sketches you would see in magazines, pinned up behind the actual sewn clothing sample.
Don't let an artistic hindrance deter you from following your dream to become a designer. When we started designing our own clothing line we lived and breathed croquis. We used them to practice drawing clothes, and we saw improvements in our sketches every day. Croquis saved us when we started designing clothes and they can save you too.