In regards to seeking counsel from the bishop or stake president, the Church handbook says that “members should make a diligent effort, including earnest prayer and scripture study, to find solutions and answers themselves.” What may be okay for one member may not be for another. That doesn’t mean the core principles don’t apply to each member, it just means that the adherence to a principle can be manifested in infinitely varying ways.
For example, Nephi felt compelled by the Spirit to cut off Laban’s head to preserve the scriptures. Could that principle, namely the preservation of God’s word, been fulfilled by other less “fatal” means? Probably. Does that make Nephi’s action sinful? Absolutely not.
I think the key with issues of sexuality is finding what the principle is that needs to be promoted and then choosing a behavior that best promotes that principle. For example in marriage, an important core principle of sexuality is that it should powerfully bond the husband and wife. Can masturbation help achieve that end? I’d say the answer is it’s up to those involved. For a single person, perhaps one of the principles regarding sexuality is to choose behavior that best prepares for a healthy sexual relationship in marriage. For the youth, the Church encourages them to abstain from masturbation and believes that to be the best route for honoring the principle of healthy sexual intimacy in marriage. I think it’s possible, however, that outside the youth, singles may find circumstances where masturbation could promote the eventual goal of healthy sexuality in marriage. Again, it’s up to the individual. For someone who has lost a spouse, maybe masturbation is a healthy way to remember and preserve past feelings of sexual intimacy with their spouse. I’m not arguing that’s always the case, my point is just that God’s core principles — those that deal with our relationships with others and with God — can be fulfilled through many different manifestations and behaviors. I think that’s one of the reasons different members receive different counsel.