Don’t behave childish. Just giving a miss-call or not sending you message does not mean that something is fishy. If this is so then rather then imaging things call him directly and clear your doubts that why you are not coming early etc..
Just because marriage registration is not happened, does not mean that he is running from marriage.
Be calm and increase your communication with your hubby.
Build trust on him. I am not able to see any reason for cheating you.
Request him to plan your honeymoon.
Be happy!! Because you have to spend your precious life with him. So by love, care, affection, smile and keeping him happy you will make your life more blessed!!