I am writing a poem for class.

It's supposed to be closed-form. I wrote a Shakespearean sonnet but my issue is not the structure but the syllabic meter. Each line ranges from 7-10 syllables. Is that against the laws of closed form poetry lol? I'm worried that each line has to have the same amount of syllables.

It's called Iambic Pentameter - - it's a rhyme scheme found in Shakespearean sonnets that must be composed of 10 syllables.

Closed form is simply superset of types of poetry such as haikus, tonkas, and well, sonnets.

So, it's not against the laws of closed form poetry per se, it's just against the laws of Shakespearean sonnets.