Defining ideal course load depends on many factors, such as when certain courses are offered, what gen ed requirements you need to meet, when you want to take the MCAT, etc. It seems like you still need at least 2 more chemistry classes, 2 physics classes, and at least 2 more biology classes, a stats class, and possibly a psychology class to meet the prereqs of most schools. That's at least 9 classes spread out over 6 semesters. Definitely consult your adviser, but it seems feasible that you could take a lighter semester next fall without falling off the curve. I see at least two options:
1. Take 2 STEM classes. Email the professors of these classes and ask whether students typically take these two classes at the same time and succeed. Ask your adviser the same thing. But this may not be the best strategy if you're not confident you can improve from this year.
2. Take a lighter semester with less than 2 STEM classes or a STEM class and maybe intro to psychology. I struggled with some introductory biology classes and got a couple of B's freshman and sophomore year. I was taking a heavy course load and did not know how to study science. Then, I studied abroad in the fall of my junior year and did no science that semester. I had a great time and came back refreshed. That spring I had a very light course load kind of by accident. It included 2 upper level biology classes that I absolutely loved, and I finally learned how to study science. Then I had a very heavy course load through my senior year but excelled because I loved the science I was learning and knew how to effectively study it. The point is, sometimes taking a lighter semester and really focusing on the few classes you're taking can do wonders for your study habits and allow you to excel with a heavier load in the future.
I get your urge to avoid humanities classes, but writing is SUPER important and too much avoidance will hurt you in the long run. There are some wonderful humanities classes and disciplines that will help you become a better thinker, scholar, and person, and you'll need to write personal statements and secondaries for med school too. These classes can also have wonderful professors (especially at a liberal arts college) that can become mentors and help with your writing. Have you reached out to international students and/or your adviser to point you towards classes/professors that are especially good at helping with writing? Does your school have a writing center? My undergrad had the option for students to make a weekly appointment to meet with a tutor do work on whatever writing they had at the time. Many international students used this and found the consistency helpful. I see you've already taken 2 English classes, which is great, but I'd encourage you to take at least a couple more humanities classes over the next few years.
For the coming semester you might even consider taking just 3 classes (if you can maintain your full-time status for visa purposes): one STEM class, one carefully chosen humanities class that you think will help you with writing, and one other class. If your grades improve you can carry your newfound strategies over to the spring and take a heavier course load.
No matter what, don't be afraid to reach out to your academic adviser and/or another professor you trust. They are there to help you and they want you to succeed.