I have found that the more I've learned about writing, the fewer "ideas" I've had. Time was, I'd start a new story every day. New characters, new setting, new this and that. Now, I have far fewer on the go, or even cropping up in my head.
That's not a bad thing at all. It's a direct result of my progress. As I've gotten better at conceptualising stories, I've realised the difference between an "idea" and a "plot". The former is great, but 99 out of 100 ideas never make it past the first three pages. When you learn to sift through the ideas and discard those which don't have the development potential - however brilliant they seem when they occur to you - you will have an easier time of it.
The trick with writing a story is not coming up with ideas. If I wanted to, I could sit down and list thirty or so "ideas" in less than an hour. The trick with writing is to find an idea which has plot potential, and to develop it into something meatier. By all means, merge several ideas together if you can. Character concepts can be put on hold until there's a space for them, settings can wait for an opportune event in a story. Even plot "ideas" can be merged in as subplots.
But, as I said, the trick is to practise working out which ideas have the going distance, until you get to the point where you subconsciously discard anything not up to standard.
I went through a phase a couple of years ago where I panicked because I wasn't getting ideas any more. Then I realised it was because instead of inspiration striking from the aether and demanding I write its idea, now, and make it the Best Thing Ever, I was able to generate stories out of concepts and premises when I actually needed something new to write, and all the rest just simmered in my sub-conscious until I wanted it or outgrew it.
I've realised now that that was probably when I actually started learning how to write properly. I've got a long way to go yet, but at least I'm getting there now. And the trick is to study all your ideas, and work out how much substance they have. Is what you've got a scene or a story?