First of all I want to clarify as someone who recently made a transition to digital, that drawing on a tablet was a whole new beast. When I first got my tablet I felt like I was learning to draw all over again and I had to look up a ton of youtube tutorials both on technique and on how to utilize the program I was working in. (Paint Tool Sai.)
That being said I do not regret it, very convenient and my drawings have improved. (I do miss the analog feel of pen and paper a bit.)
Also as someone who was completely frustrated to the point of quitting drawing all together due to lack of improvement maybe I can help. First of all Pinterest character design was a huge help. There is so much reference material and a lot of just drawing tutorials that after a couple months of utilizing that I already felt I made more progress than I had in the last 5 or so years of drawing.
If you are overwhelmed with where to start, anatomy is always a good way to go. Understanding that will help you no matter what you go for, either realistic, anime, or a western cartoony style. It's a case of knowing the rules so you know which ones to break to create an interesting style.
Someone mentioned earlier about taking some college drawing courses, and that isn't a bad idea. (Depending on who you talk to not compulsory.) If you do go down that route, I'd recommend a figure drawing course. I never took one myself, but I've seen many artists drastically improve after they did a semester of that. (If I go back to college I will definitely.)
In closing don't be discouraged. In my opinion you have a good foundation and you seem like you want to improve.(don't we all!) There are so many web comics out there now that are super famous that started with less than stellar artwork. Just by putting yourself out there and beginning a story you have made a big step. The road of the artist is a bit of a masochistic one, but I think everyone can agree it is totally worth it.
(TLDR) Study some anatomy, keep practicing, and keep an open mind.