This dream seems to revolve around themes of anxiety, social dynamics, and the pressure of expectations, particularly in a school setting, which is often a metaphor for growth and learning in life.

1. Being Late: Your lateness might symbolize feelings of being unprepared or overwhelmed in your current life. It could also reflect concerns about meeting expectations—whether they are self-imposed or from others.
2. The Halloween Parade: Halloween is associated with masks and transformation. This could indicate a desire to express yourself or a fear of judgment. The parade represents a social event where you may feel the need to perform or fit in.
3. Ex-Best Friend: The interaction with your ex-best friend and her sister might suggest unresolved feelings or conflicts from past relationships. Their questioning could symbolize feelings of being scrutinized or judged by peers.
4. Changing Rooms: The bathroom is a private space where one typically prepares themselves. Your struggle to find a suitable place to change reflects feelings of vulnerability and the pressure to present yourself in a certain way.
5. The Thai Exchange Students: This could symbolize cultural differences or feeling out of place in certain situations. You may be navigating interactions with people from diverse backgrounds or feeling like an outsider.
6. Teacher and Superintendent: The authority figures represent societal expectations. The urgency from the teacher about needing to be in class could symbolize your own internal pressures to conform and succeed.
7. The Freshman: Your reaction to the freshman asking to change reflects feelings of frustration and perhaps a sense of being overwhelmed by others' demands. It could highlight a struggle with boundaries and self-assertion.
8. Ending: Finally, the relief of making it to class just in time suggests a desire for acceptance and acknowledgment, especially from peers. Your friend’s comment reinforces a part of your identity that values punctuality and reliability.

Advice: Consider what areas in your waking life are causing you stress or feelings of inadequacy. It might be helpful to reflect on your relationships and set boundaries where needed. Finding a balance between meeting your own needs and those of others can lead to greater peace of mind.