Is this normal?

I am new to being a sub. I’m currently in college to become a teacher so I thought that this would be a great opportunity to have some sort of experience. I do not have full time availability ( college classes ) so I’m unable to work two days out of the week. I keep getting jobs for the two days I’m not available and the jobs themselves are hard to come by. I wake up early In the morning there’s nothing on the app. When I do get a notification for something it’s already taken by the time i open the app. I thought that there were more opportunities than just barely one job a day that I can’t even get. Also I’m supposed to at least work 4 days a month. That’s hard bc I don’t have full time availability and lack of jobs. I don’t want to just give up only because school just started and not a lot of teacher are going to be absent on the first month, but also I don’t know how I’m going to work 4 jobs for the month. I also wanted to ask if it’s normal to barely get any jobs or if it’s my app (Ess)?