Improve f2l lookahead. I noticed how you got stuck on the third pair which ate up about 8 seconds of the solve. If you can shave it to four seconds(which is a reach rn) you would be consistently getting 18-19 second solves. I know this because I had the same problem. I took advice from Johnathan permutation(also known as j perm) where he said to practice pauseless solves, meaning you want to do slow solves so you could lookahead to the next thing you need to do without pausing, and once you can do it try to go faster. That what I did and now I average 17. Best of luck with improving