Is there anything in your life, beyond your not being chaste, that you feel might be keeping you back in your spirituality? Usually, you can feel it if such things are in your life. The problems you're having with chastity might be symptomatic of other problems you're justifying to yourself, or rationalizing yourself into keeping around. For some people, as an example, competitive activities such as video games might be a barrier to spiritual power.
What is your first priority? Is it pursuing a goal that does not align with your desire for purity? If there is any thing of a higher priority in your life than becoming pure, please, re-evaluate your activities. Give them up if they stand in your way. Find local friends in the Gospel, and engage in conversations about it - principles, testimony, and experiences - make the Gospel a focal point for your intellectual life.
If there is anything weighing you down, divest yourself of it, and unburden your whole soul in prayer to your Father. Pray with all your might to receive of his Spirit. See how you feel then.
