"I don't think I'm a good developer."
I think a lot of developers out there think this or something similar at one point in their career. Mainly during the first few years when they started out. Maybe they just started their first job or even thinking of moving to a second job.
Here's my advice if you're one of those who think this...just relax.
Yes, I definitely have done this myself. All through college, when interviewing for my first job, during my first job, interviewing for my second, and during the first couple of months of my second. Seems like a lot of times worrying and doubting yourself, doesn't it?
It's kind of nice that you worry about this stuff. It means you actually care, right? But just think, if you weren't as good as you may think, how would you have gotten the job you do now? How would you have been able to stay there for as long as you have?
If you still feel the same about your skill, take this opportunity to learn new stuff. The internet has tons of stuff online to get you started. One tutorial doesn't make sense? Go to the next one.
So go on, challenge yourself. After doing that you'll become better than good enough.