Yep their is no deffinitive answer on how to gain a certain goal in a set amount of time, like your 1X1 in 3 months.
I have been around LONG enough to know its not pratical.
Best thing to do, is work CONSISTANT, INTENSE and have TIME and PATIENCE.
Use exercises you LIKE, and also what has worked for you before.
After the 3 months you should have something new down their, even the 1X1?? who knows.
Have you ever tried
hanging? the bib hangers are very good, and
hanging can really get length gains....also maybe try clamping or some of DLDs girth super-sets for that area......maybe even do DLDs length super-sets and girth super-sets?? if you read through the exercise thread in this section up top [sticky] you shall get many ideas of what to perform.
Also going into the routines section, and looking about will give you ideas of how to mix it up.....check out Crazyeds thread, phillys thread, dlds thread and the sticky ones for the best ideas.
Goodluck, and if you need advice than PM me.