Disk Capacity 500 gb falls to 250 gb after deleting files

I have a 13" MacBook Pro Retina - bought 9 months ago but I guess it's a 2013 model - 500gb hard drive.

As I constantly get "your start up disk is almost full or full", and deleting files all the time, I delved a bit deeper to find doubled up files etc.

I access my iPhoto Library - that was 187 gb. & went into Preview etc., where there were hundreds of files. I removed as many as I could, then removed the remaining folders & files in iPhoto.

When I emptied trash, it said approx. 215,000 files would be deleted. Seemed excessive but I did it anyway.

So, having done that, my Hard Drive capacity is now showing a 250 gb capacity - with only 5.1 gb free. It seems I've lost 250 gb - is there a fix??