You are young. It is normal to want to be single at your age and take time to get to know yourself and experience all life may have to offer you. You need to clearly inform him that you are not on the same page as him. He has no right to ask you to push back your plans to wait for him. That is simply unreasonable. If you are not ready for the type of relationship he wants or maybe believes he is in with you. You must be honest and let him know this. Try to be gentle in your approach..he may be angry or upset or shocked even..but if he is a person who wishes to remain in your life..given a small amount of space and time he should understand and be OK with it... If he acts possesive, or inappropriately overly irate or makes threats towards your or himself...remove yourself quickly. If he persists and or you truly feel he is a danger to you or himself call the authorities and cut all lines of communication. But hopefully he is not a bad guy...just let himself get lost in the possible future and glowing aura of new romance.
Be Safe! Be Well! and Keep Writing!
-LITW