Being "behind" in level of classes compared to peers

If you are aiming for the most highly selective Universities (HYPMS, etc.) and LACs (Williams, Amherst, etc.) in the country then this might matter a little bit - but only if you also have superb standardized test scores and GPA, class rank, EC’s, essays, recommendations, etc.

The tippy top schools care whether or not your GC checks the “most rigorous” box to describe your classes.

The vast majority of schools, probably well over 90% of the colleges in the country could care less.

If you are extremely focused on the tippiest of the tippy top schools, then you can do what many students do to get ahead: self study, either by yourself or with online classes. Then start looking for summer (seems like that may be difficult with your family situation) or school year internship, research and volunteer opportunities.