18 Guna milan out of 36 is minimum of what is required for marriage. However Bhakoot and Nadi dosha is not good. No pandit and astrologer will suggest marriage. However if the Bhakoot and Nadi dosha get canceled then marriage can certainly be considered. If the Bhakoot and Nadi dosha get cancelled then the malefic effects of these doshas are not felt in the relationship.
Also please get a Grah milan done to know your complete Horoscope matching in detail.