Definitely don’t drop the class. What’s worked for me when my stuttering has been particularly bad is to just let the teacher or anyone listening know that you have a speech impediment and to please bare with you. I personally have found most people are a lot more accepting and patient when you let them know it’s something you struggle with. And anyone that isn’t is not worth your time. As for the problem with your sibling, you could try and switch to another section of the class at a different time, if it’s possible. Talk to the teacher about your predicament with getting to class on time, most are happy to help. You don’t even necessarily have to explain the part about your sibling. Just leave it at “unreliable transportation.” Good luck in college! Stay on top of everything and you’ll have lots of opportunities to improve yourself.