PH at too young an age can stop bone growth, and many think it will limit your natural muscle potential. Maximize natural potential, then use PH or steroids to go beyond that. Wiat until you're at least 20-21. Get your diet and training in check. Read all you can.
Flax would be a great idea. I like Udo's Oil which you can get from netrition.com, or total EFA by Health From the Sun. Actually flax seeds are better than the oil. You grind them up in a coffee grinder. You can only grind enough for a day at a time because they go rancid, once ground, very quickly. Oils can go rancid as well. Seeds are much more robust, and cheaper too. My wife's grandfather hooked me up big time with a new flax source. You can get 50lb bags of flax seeds for $7.50 at most grain stores. See if you can find one by you.