Dear Isadora,

It's normal to feel aprehensive when you have had a previous negative experience. It sounds like you had a tough time. With breastfeeding, as with anything, knowledge is power. Once you understand how it works, you can feel more in control. So you have done the best possible thing, enrolling in that class.
Try to hang out with some mums that are breastfeeding. We learn by seeing. Talk to them, find out the issues they had and how they overcame them. ABA is a great place to help normalise breastfeeding.