How to Make life better than before? Asking as a student.

I'm a student. I wished to have admission to a Medical college but couldn't. I have Questions and ambiguous perceptions about life.

-I go to attend graduation classes in the morning.
-I do part time job
-Also take classes again at night(To make myself much busier...u know why...dont wanna mention).

Still feels insecure and like all the time over cautious that either I would do good or not, like mentally...
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My classes are about to start. It would be difficult to get here for that much.
I feel caged.
What should I do? I believe wasting my teenage watching to porn and not studying effectively sucked me and EVEN now I'm not enjoying that much like doing what you wish for.
I want to learn a skill to get rid of Job.

What skill can give me income?
Pls do reply because it is about people who know, what we are going through.
I wished...to get good grades like others do but watching to porn made me helpless and restless to contribute further.

What management can be done?
How people manage in between.
Look, we don't know each other but can help each other, and that matters.