You are only experiencing what all of us at some stage in our flying activities have felt. When I started my ppl, I was stuck at 15 hours, desperate to go solo, but could not. Reasons - availability of aircraft, availability of instructor, weather, your time, and motivation when you are not progressing quickly enough. It is the biggest issue of learning to fly, continuity, within Europe. Suggestions - keep on going, it will happen, go to the states and do it as an inclusive package, buy your own aeroplane, and get an instructor to teach you in that. Keep going to the 'red line', and keep involved in all that is going on.
Good luck!
