It's tough when there is a delay between your class and your first jump, as there is a lot to remember. However the first jump course provides you with information you may need to save your life. What was it that you "didn't remember"? (Don't answer that, just think about it.) If it was emergency procedures, for example, not remembering could get you killed if you are unlucky and have a malfunction on your first jump. Your radio may malfunction, and you'll have to remember the landing pattern on your own. Did you review the material before going to the drop zone? Did you (perhaps unintentionally) convey the impression that you didn't take things all that seriously to your instructor? In any non-tandem jump, you are completely responsible for getting to the ground and back to the hanger safely. Your instructors cannot deal with a malfunction, or steer you back to the landing area, or ensure you flare on time etc. If they are not confident that you could do those things unassisted, they are doing their job to have you wait until you have mastered the first jump course material.
If you really want to give skydiving a try, you won't let a minor setback like this discourage you. Assume your instructor has your best interests at heart, and they did not feel you were ready to jump. Review all the material, and go back with the goal of proving you are ready for the next step.