You sound very much like me... I was a ME grad from a top US engineering school, with a 3.5 gpa. I worked my way through school and was/am very proud of the accomplishment.
I worked in aerospace for several years, and also a couple of years in the power industry. I started flying for fun, and like you devoured any source of aviation knowledge I could find and loved it!
After working as an engineer for about five years, I made the switch to professional pilot. That was almost 10 years ago, and I am now a captain at a large regional. I really enjoy it, and am VERY glad I made the switch. I'm now working towards getting on at United or Delta this year.
Anyway, feel free to ask me any questions... You can also send me a PM, and I'd be glad to exchange phone numbers and talk to you about it. It's a big decision, and I know you probably want to make sure you think it through thoroughly. Best of luck!