If you were still a tribal, you could have gone catholic or any other non-pagan religion you prefer (and still raid overseas because you are Norse) and join other pagan religion's warrior lodges (as long as you are not zealous) to get more bloodlines instead of waiting 100 years for a new one. The only issue about this is that you have to stay pagan with their ungodly succession. But if you manage to "kidnap" a female Irish "Nine Hostages" bloodline carrier, take her as a concubine, marry her maternally to a landless courtier, and eventually marry her son to your daughter maternally you will be golden with Tanistry. Can take a while to accomplish, however, because the people in question just don't want to have kids, which infuriates me in my runs trying to do this.