I got discouraged for awhile and just stopped coming here for a bit (but then I felt like I was missing out and I'm addicted once again). I get frustrated about the whole length gains for myself, but overtime I've come to realize that the only person that really is concerned or judging my 'progress' is myself. So, for example, my length hasn't changed to much over time, but the overall health of my hair has done a 180...it looks great, and I know it!
I'd rather have healthy hair than long ratty hair anyday. So now I just make sure that I'm keeping up a 'reasonable' regime, and just appreciate my gains when I do see them. I can't make it grow faster than nature intended, but I do have control over my daily care.
I think reflecting on your goals, why they are important, but at the same time reviewing why you have a rigid time constraint is important. I think its better to align your goals with your methods, and with a less focus on outcome. For example, instead of making a goal "I want 3 inches by winter" you could make your goal "I will make sure that I do x, y, z consistently so I have to cut less ends off by winter".
I hope this is encouraging and not preachy....I guess, the way I made myself feel better is stop being so hard on myself for not reaching length goals, but instead rewarding myself for keeping up a consistent care regime.