I understand almost everything but I can’t say very much

Is there something in particular that stops you from speaking? Are you too self-conscious to speak up? Are you worried about your skills? Could the problem be that you rarely get to use the language in a real–life context. Reflect upon situations you have found difficult, work on the aspects that you feel are blocking you e.g. pronunciation, vocabulary. Try to be brave and start looking for situations where you have to speak up, it may not be as bad as you thought.