A sweater worn to help keep you warm can represent:
- Self-protection, as in protecting one's self from others' cold or negative emotions the way a jacket protects a person from cold temperatures
- Self-nuturing, self-care
- Measures towards emotional, mental, physical survival
- A timeframe when you often wear sweaters
Also pay attention to the main characteristics of the sweater (color, condition, style, etc.) for clues to its meaning.