It has been reported that Umrah is expiation from sin and this is a manifestation of God's mercy and kindness to His slaves when He legislated for them certain acts of obedience that lead to forgiveness of sins. This is a common message in the religious texts. Despite that, a devotee should be afraid of his sins so he may become closer to Allah's mercy and acceptance, and this may be an encouragement to perform more good deeds and avoid committing sins. Almighty Allah said: "And those who give that which they give with hearts afraid because they are about to return unto their Lord; these race for the good things, and they shall win them in the race"(23:60-61).
It is not obligatory to obey the parents. What is obligatory is to be dutiful to them and to have a good relationship with them. Nevertheless, we advise you to convince them and take their permission as much as is possible as this is one of the means of receiving divine blessings.
If the contract was done without specifying the time then the marriage becomes permanent, and the marriage can be ended by divorce and the obligations of divorce like Iddat and others should be observed.