I found that climbing shorter sessions more frequently and consistently helped (going from 2 LONG sessiosn to 4-5 mid sized sessions a week).
I think 3 months to V1-V2 is not actually particularly bad progress, when you think about it, if you climbed your max every week thats only about 36 climbing sessions! Assuming each of those were 2 hour sessions thats only 72 hours of climbing!
How can you expect to be really good at anything after only 72 hours of doing it? However, you are setting up a strong base and you should not be concerned about progressing faster and certainly not concerned about strength. Once you get into gym lead climbing, trad, and sport and crush some outside rocks, your perspective changes a little. Crushing a 11A in the gym doesn't transcend to an 11A outdoors, if you are still sketch on your gear, and don't have the headgame for it.
I suggest reading 9 out of 10 Climbers Make The Same Mistakes by David MacLeod
https://www.amazon.co.uk/Out-Climbers-Make-Same-Mistakes/dp/095642810X Dave Macleods book is pretty solid and best read before you make the mistakes he talks about :D
Alos run, not marathons (unless you want to) but cardio helps build the stamina for long routes no one tells you you really will like having. Side affect is it builds all your leg muscles too in a supportive core affirming way.
I started with 9 out of 10 climbers make the same mistake by Dave MacLeod. Great read and gives a lot of stuff to think about. Afterwards I got Training for climbing by Eric Hörst and Make or Break by Dave MacLeod which are also great books. Recently I got a copy of The Climbing Bible by Martin & Stian which also contains a lot of information.
Climb more
And read this: https://www.amazon.com/Out-Climbers-Make-Same-Mistakes/dp/095642810X
http://www.davemacleod.com/shop/9outof10climbers.html
https://www.amazon.com/Out-Climbers-Make-Same-Mistakes/dp/095642810X
If you order it from his store you'll get a signed copy.
For sure, man. "9 Out of 10 Climbers Make the Same Mistake" might be helpful as it focuses on becoming an overall better climber (and getting over that pesky fear of falling!). "The Self Coached Climber" is a good one too because it focuses on training and movement drills (and has a sweet DVD ).
As far as anchors go, I really like Craig Leubben's book. It's on the same level as John Long's anchor book. Has lots of pictures, good explanations, and at the end of each chapter a checklist of skills you should be able to do after reading the chapter. Just make sure you get an experienced climbing partner to check your setup (ideally someone who has climbed in the area you're climbing at).