Oh I can so relate to your post
I always feel like I can never compete with people who update more frequently and I'm afraid that my subscribers (or potential ones) don't want to wait so long for updates (even though 2 weeks isn't that long right?) - I'm glad I'm not the only one feeling like this...
I work full time too, and at the end of the day after doing all your chores and stuff, all I have is about 2 hours (or 3-4 hours if I want to be super tired the next morning) to draw.
And yeah, it can be hard to find time and motivation to draw. But when you do, you can be even more proud of yourself for doing something productive at the end of the day. Plus, drawing is a huge stress reliever for me, especially when I can work on my webcomic. And even if it's slow progress, it's still progress!