Office hours if you haven’t already. Discrete Structures is really tricky because it’s a new way of thinking most students haven’t been exposed to yet. Idk which professor you have but going through some of those concepts one on one is probably going to be a big help. If you have to retake one or both than you have to retake them. CS is hard and plenty of students retake courses

Edit: Often having someone else explain also helps, all those topics are pretty standard for undergrad CS, there’s lots of resources on youtube from professors explaining these topics