Thanks everyone!

What a wonderful insights and tips! I really feel like I'm a member of very supportive group.

I totally agree with consistently practicing everyday no more than 30 minutes per day, because some days I was practicing more than an hour and ended up pain in my arms and a little sore feeling of am I really able to learn guitar? I learned overpracticing without really understanding my skill level can actually discourage me.

The second thing I learned was using the metronome consistently. RonaldR's point was so on point, I have to master the basics and move on to the next level. I thought I was already comfortable with changing C and Am, Em and A quickly, but when I used metronome, I realized I actually need to practice on these chords a lot.

I'll be keep practicing and sharing my journey.

And thanks for all the instructores as well!