Ask HN: Is this depression? What should I do?

Hi HN!

Long story short: I'm a 27 years old guy who graduated from the top schools of my country and who likes development and marketing. I quit my job 2 years ago to work on my own projects, and I succeeded. After 6 months of work I released an information product that made me on average $3k per month until recently.

After the release of my product I decided to take a 2-3 months break from working. However this has transformed into a 1.5 year break now where I've done almost nothing.

And now that sales of my infoproduct are almost non-existent, I really need to get back to work. I see basically 3 main options, but I somehow don't like any of them: a) Go back to work on my project that has 10,000 email subscribers that have not contacted in a while b) Start applying to regular jobs like Product Manager but I don't know how they are going to react to my recent experience c) Start a brand new project.

I feel lost, bored, and unmotivated. Is that what depression is? On the other hand I go out with friends, have great time with my girlfriend, I read a lot of books, I keep learning new skills, and spend way to much time on HN/reddit/youtube.

I've been in this really weird state of mind for more than a year now where I do nothing work-wise. This is obviously not sustainable, and don't know what to do to change that... Any advice?

Thanks for your help!

TL;DR: I stopped working 1.5 year ago after a successful side project, and now can't get back to work.