This? This is perfectly normal. I think we all do this at some point - or, if you're me, 75% of the time. Making a webcomic can be scary - as can any creative endeavour - because hey, you're taking something you worked hard on and love a lot, and showing it off to strangers on the internet.
As for decent reading response... Posting on Tapastic is a good first step - there's an established community, and people are more likely to find your comic - but you still have to promote yourself like mad. Post in the forums, use your social media accounts, talk about your comic until you're blue in the face.
I plan, meticulously.
I've got an outline of my entire comic (which gets revised occasionally, but I know where it begins, I know most of what happens in the middle, and I know where everything ends), and then I plan it chapter by chapter. I go over the storyboards and tweak things. I keep editing the dialogue right up until I post it. I have a 50+ page buffer, so that I'm nearly two chapters ahead of my readers at all times.
Knowing where I'm headed makes it easier to keep going. It minimizes the risk of artistic and writer's block. I still have slumps, creatively, but if there's one thing I've learned over the years, it's that the only way out is through. Blocks don't go away if you give up. Blocks go away if you work through them. It doesn't MATTER if it feels like a slog, or if everything you touch turns out terrible; every time you pick up the pen, you're practising. You're learning stuff. You're getting better. And eventually, you get good enough that things stop feeling terrible.
Allowing yourself to take breaks is important too, of course - you don't want to burn yourself out, of course! - but know that the only way you're getting rid of that block is to keep drawing.
