Sufficient for what? Is your goal to find a Java software engineer job or you want to get high marks in a university assignment? Those are two separate goals. If latter is the case, what does your assignment require?
If you are doing Leetcode, it requires a significant amount of time to "master", if you are at a stage where you can solve most medium difficulty problems then I would say yes now is the time to work on some projects. Knowledge of DSA is very important, it worth investing time.
With regards to ChatGPT, I find it underwhelming and many times the code it produces contain some type of bugs. However, ChatGPT plus is different beast, it is night and day better and can radically speed up the learning process. I would recommend getting it(around $20/month). I am using ChatGPT plus everyday for my university coursework and its unbelievably good. It is almost like a programming partner and can be your "tutor". End your netflix subscription(or any other useless subscription) and get the plus version. Also I shared the link to stackoverflow which contains recommended Java books.