If a person is asexual or has very low desires it is completely fine for them to be single as they will not be able to fulfill the rights of the wife.
Marriage is not a Faradh. It is not necessary. The hadith about Marriage being half of your diin is taken out of context. The hadith only means marriage will keep u out of haram troubles. Which we have found out so far as not always. Married people cheat and do haram all the time.
U can remain single and worship Allaah swt. U would have passed your test.