There are a lot of universities that are very good for computer science. I have worked in high tech for my entire career. I have worked with coworkers who had graduated from a very, very wide range of universities. You do not need to attend a “top 20” university to do very well in high tech / computer science.
Once you are working, people will care about whether your code is relatively bug free before you try to merge it into the main line. They will care whether you are reasonable to deal with as a person. They will have forgotten where you got your degree and will not really care where you got your degree (which is why they will forget it).
You are taking a very tough combination of courses. Do the best that you can. Then don’t worry about it.
To me, a “top 20” university at this point looks unlikely, and very much not necessary. There are lots and lots of other universities where you can do very well.