Mama, I really feel for you, this sounds like you're going through so much, and that ER experience sounds terrible. Please talk to your OB again about your concerns, or get a second opinion from another trusted doctor before your due date, this is serious enough that you deserve to feel confident about your birth plan, and your doctor needs to hear how scared you are.
A few of us moms have dealt with hemorrhoids during pregnancy, and honestly, it's one of those things where your doctor knows your exact situation best, especially at Grade 4. Your OB might have good reasons for recommending vaginal delivery, or she might adjust her advice once she sees how anxious this is making you. Either way, you have the right to understand her thinking and to explore all your options with her directly.
For now, keep taking what your doctor prescribed, rest as much as you can, and don't carry heavy things. But mama, the big decisions about delivery, that's between you and your OB, and you deserve peace of mind before labor starts. You've got this, and you're not alone in worrying.