My teacher is always dismissive of my problems and always redirects me to the school counselor. How can I get her to understand me more?

Your teacher might think that she is not the right person to help you; that the school counselor is more fit to help you with your problems. She might even have received instructions from the school that if a student approaches her with personal issues, she has to refer them to the counselor. So the next time she refers you to the school counselor, you might want to consider saying something like: "I'm not telling you this to ask for help. I understand that the school counselor is more fit to help me with this. I'm saying this so you know what's going on in my life, so you can understand why I might do things the way I do and [whatever more you want your teacher to know]."

The best way to help someone understand you is by communicating with them. Advising them how they make you feel, and what you would like her help on. It is possible that your teacher may not know how to help. That may be one reason as to why she redirects you to the school counselor. Some people may not know how to help, or they may feel like they are not the best people to help depending on the certain situation. So they refer you to someone who has more skill in the area, someone who may have better knowledge, or may be more of a help in that area.

If your teacher is being dismissive and referring you to the counsellor it may be that they feel unequipped to deal with the issues you are telling them about. Schools also have certain policies for some problems which mean teachers have to follow certain steps, such as referring you to the counsellor rather than having the discussion with you themselves. If your issue isn't something you feel the counsellor can help with, discussing why you think this with the counsellor may actually be a good first step. They may be able to help you more than you think. Also, it's important to remember that teachers are humans, and some humans are better or worse at handling situations than others, it could just be your teacher's personality making them dismissive.