My brother is diagnosed with dysgraphia.
It's a legitimate disorder as equally obstructive as dyslexia.
He's slow to write and has difficulty maintaining shape and size of letters. Often his writing is bad enough that it's illegible even to himself.
Another side effect is it inhibits his ability to draw. His drawing skill is equal to an 8 year old despite being 18.
If you think you have it speak to your school nurse/counsellor or even your doctor about getting it officiallyt ested and diagnosed. At school they should provide you with a laptop for writing, and one in exams (or the option of dictating to someone else).
If you do have it then make full use of any support you get or else you're not giving yourself an equal chance thaty our peers get.