Istikhaara for marriage

We carried out an istikhara for my son almost a year ago for a college girl he was interested in. The Aalim said no. My son got very disturbed and heard from someone that istikhara can be repeated after some time. During this year almost, he prayed five times and performed umrah with the family and did istikhara himself and saw himself offering prayer. He says he is satisfied and the answer is yes from Almighty Allah. He only resolves around any option confirming his yes but we the parents still wish to seek guidance. We want some responsible authority to say ok before we take decision. Please help us!!