Sorry in advance for the novel!
I'm also an American student and my qualifications were almost exactly the same as yours so I can try to help. I applied this year as a graduate from an American college (where I studied film!) but it was for an undergraduate degree (Law) so I had to do it on UCAS and they looked at my high school stuff.
Anyway, did you just finish taking APUSH? Because there's a subject test for that and I don't think they mind if the SAT-IIs are in the same subject as the APs. Are you taking Lit next year or did you already take it? If you can fit it in, you should definitely try to go for it. The thing about these tests that's pretty annoying is that schools assign different "levels" for different kinds of APs/subject tests. So a 4 on APUSH is worth more points than a 5 on AP Stats in UCAS tariff points (
here's an example from Exeter). You definitely want to take subject tests so you can boost your tariff points (obviously they can't calculate points for you the same way they can for UK students because you're doing a different diploma, but I'd imagine they'd take them into consideration for comparison purposes). As someone else mentioned, most schools that accept/look at the ACT will want 27+ so you seem to be in the right neighborhood for that. Try to take it fairly early so you can retake if you need to.
I applied to schools in Scotland and they seemed to require fewer tests than did the English universities I researched so I'm not sure how much my advice will be able to apply to your situation. I would imagine that Film would be less competitive than English or History, though you will probably have to decide between production and studies (that will make a difference, I think, as production is less academic than studies/theory).
Basically, each school is different; some schools will care more about tests, while others will care more about references and personal statements. You just have to hope that the ones you apply to will find things to appreciate about your application. I think that they have to be relatively flexible with international applicants because schools and qualifications are so different from their own; furthermore, the US is so big and every state is so different, we can barely compare students from across our own country. Also we don't take tests as seriously in the US so it's just not really comparable. And they know that. If you put a lot of effort into your statement and you get a glowing reference letter, it will probably make more of a difference than it would for a domestic applicant.
That being said, I agree with the previous posters who said you could set your sights higher. Definitely check the requirements for each school, but keep in mind that those are guidelines rather than straightforward rules. In a lot of cases the different academic departments will have their own requirements and admissions teams so it's really hard to know what they really require. I think personal statements probably matter a *lot* for arts subjects so make sure you articulate your interest as sincerely and enthusiastically as possible. They want to know that you know what the subject entails and that you're sure it's what you want to study.
Long story short: your SAT score is in the 94th percentile. You've passed both your APs. Your GPA is good. You will probably do well on the ACT and you have plenty of time to craft an excellent application. Take the subject tests, do a ton of research, pick 2 safety schools and 3 reaches/matches and you'll probably do well!