Saying this as a current high school senior: please, please, please don’t stress about college right now. You’re only halfway through 8th grade; you have four whole years to think about higher education. There’s no sense in stressing about details like first semester grades now, especially when colleges won’t even see them.
I absolutely agree with other posters that you should seek out tutoring, because struggling in math is a frustrating feeling. But don’t do it for a school that you won’t even apply to for a few years. Do it for yourself, and your own education. I can tell you from firsthand experience that worrying about college so early on will only lead to burnout and overworking yourself.