I'm 16 btw.

This school year has been so weird. I've felt quite stressed about how I can sort my issue out with uni but I've started enjoying School much more this year but I just feel sad whenever I'm alone or im home. My family is amazing and I'm close with everyone but idk I just feel so low all the time recently when I'm not around certain people or certain situations. Anyone with advice. I would say this started to get bad like 2 weeks ago or a week ago