What should I learn to become a web design expert? I am from engineering background

I'm a computer science graduate having a passion for web design. Almost two years ago, I started learning web design. I designed few websites as well. Every day I try to improve my designing skills a lot.

I just want to become a highly skilled, professional web designer!

I'm good at programming and I can design good aesthetic websites as well. As I told you I've been pursuing webdesign for the past 2 years (through online blogs & e-books). I have a good knowledge in layout design, color schemes, grid systems, and obviously, coding.

One thing which makes me feel weak is that I'm not a graduate from an arts or design school.

Can I become a skilled designer who is able to design as designers with an arts background do?

Can you suggest me something which takes me from a newbie to the advanced level?

I'm not a newbie in designing! I know the basic things and I'm also working as a junior designer. I just want to learn more and more to become an expert web designer.

I hope you can give me proper guidance & suggestions..

Thank you.