Hi,
Its been a question that has me thinking overtime. I am a web designer/developer. Not a awesome one. I don’t have a magical photoshop designing skills, jQuery skills for wow factor or good html, css or php but i get job done.I might say i maybe good in wordpress but that too to some extend as i know where i what. I think its been a total 6 years and i have worked on many websites and from full time job to full time freelancer. yet i am confused.
With knowledge of designing and developing. I am not good at any and i keep on juggling between both. I can’t decide what i want. CSS and HTML i love because CSS totally changes the layout. its like a paint on canvas for me. CMS like WP,Magento or PHP or MySql are interest to me as they bull Data and store Data etc. I am totally confused as i am not good at anything (though in css i am). I wanted to ask, how to asses yourself and find out what inspires you.
p.s - i go over so much over something to get it. sometimes i don’t and that make me think. maybe I.T isn’t my thing.
Probably you’re undervaluing yourself. Regarding what you should choose… well, I’m not the best person to give you advise because I’m sort of in a similar situation (up to a point).
The thing is if you like your job or when you get in front of the computer you’d rather be somewhere else… and if the second, why… maybe it is not that you don’t like to do pages but it is more a case of dealing with customers…
Being good at something is a matter of time and practice. You should dedicate time in those areas that you’re not good to improve. So if you still want to do the whole lot, you should program some time to learn more about MySQL, JQuery, etc. With time, you’ll be terrific on all areas although for sure there will be one that you will excel.
But first things first, you should question yourself what job will get you out of the bed with a smile on your face and thinking “Great. I’m going to work” 
A lot. i have a love for web and interactivity. the way data flows. like on facebook or ajax. i love animation like 3D. i have die hard passion for drawing but i am 50/50 is all.or little less than 10 % in ajax,DB and 0 is drawing or animation.
Do what you can believe in. It takes courage.