I had the same problem. Tried to be a Dom but failed at it (I had the opposite to you - I was really good at thinking up ideas but no good at having the personality to carry them out), thought I may have been a switch and then finally decided that being a sub was what I really wanted to be. However, I still have ideas about what I would like to do to women I had under my control, the image of bound and gagged women turns me on as much as being bound and gagged myself. just never found anyone I could really practise with.
Pigeonholing is sometimes not easy to do and as stated is not always the best way to do things. Sometimes it is best just to be 'you', a pigeonhole of one. I don't think many here really take the labels seriously or insist that you are one or the other. Most accept that if you say 'I am X' they won't say 'You can't be X you don't...' But then this is a very relaxed and relatively liberal BDSM site. There are some sites (or maybe some individuals on some sites) out there where you would get flamed for allegedly claiming to be something they thought you were not.
In your present state, I would say experiment and play around - see what you enjoy the most and do it. Try new things you like the sound of. Ask if someone would Dominate you, ask if someone wouldn't mind being dominated by you. Maybe get someone who is an experienced Dom to give you some ideas or guidance. Your lack of ideas is fixable with experience and there is a lot of experience crammed into the heads of the members here. Use it. Just don't get distressed because you haven't found a niche yet. You will soon enough. Took me 8 years at least and I am still not sure.