No worries, bro. Height dysphoria is really hard. While I believe in therapy, I struggle to believe that therapy can fix a lifetime of insecurity about one single quality that we could never control and therefore always felt defeated by.
I'm guessing you're asking about quad-lengthening. In terms of pure technicality, the situation is such that even if you are below support line for the weight, there is apparent potential that the nail can bend at anytime. From what I've heard, quad lengthening (even with Stryde) is seriously difficult both physically and especially mentally. The pain and lack of mobility is very difficult, especially for that amount of time. The healing and risk of complications furthers as well. Even with just Precice, I'd recommend that for best results, you assume that you will be wheelchair-bound. Even if you are under the maximum-load the nail can handle, you have to consider other things such as force and external weight. Imagine this - you're standing on the nail at 115lb and you pick up a 20lb even momentarily whilst standing. To the nail, you're now 135lb. You accidentally overcompensate on the legs and add more weight through force, now you're even heavier on the nail. The displacement of weight in your body is important.
I'll say it like this - if you are honestly ready to go through several months of true immobility and serious pain and you are mentally stable and prepared, it's possible. But, at no point will it be easy. It's not impossible, though.