What to do when I feel sad and I don't know why

I might be depressed but I don't know myself? I'm getting scared sometimes.

Recently, I feel unhappy and feel down or empty but I don't want to tell my family. I always want to sleep and don't want to do anything. I hope it's just a normal unhappiness for awhile. It used to happen to me like 3-4 years ago when I couldn't find the job I loved. It's not completely the same. Probably because of my study pressure or because I always stay home all days since the pandemic.

Since I noticed I fell down recently, I started doing something different to entertain myself such as:

1. Gardening and cooking

2. Watching comedy dramas or movies

3. Talk to family more than before

4. Meditation before sleep

5. Doing exercise 3-4 days a week

6. Self-love and eat well

7. Don't overthinking

8. Be positive

9. Don't study for awhile

10. Stay away from social medias

I will keep following the list above until I get better. Let's see if it works well after sometimes. I hope it will work and I will be back to normal life like before. I will update my condition within few weeks. If still not work, probably I need treatment. I won't let myself falls into depression because I heard that depression is very serious and very difficult to be cure.