@killmyego, Sure mate. It is possible that your plant lost a lot of time in early growth stage and now prefers to focus on flowering. Autos do that I am afraid. You are also an outdoor grower as your grow description says, which means your plant is not guaranteed to get proper, intense sunlight through he day - and honestly september sun is not great for growing anything, it is usually when plants naturally die or prepare to hibernate, as days get shorter, colder and the light is weaker. If your plant gets less than 12 hours of good sunlight it will grow very slowly. As for today, the day is about 11 hours and 50 minutes long, which means your plant only gets a couple of hours of direct sun.
My suggestion would be to get a lamp for this one, you may still be able to help her grow during flowering. I noticed my plants still grew quite a lot during first 2 weeks of flower (pretty much doubled in size) so there is still hope! If this is just one plant, you could even get a 100W LED - unless of course you are more ambitious or your budget allows to have more fun.
I don't see any possible issue except lighting, the plant looks very healthy otherwise. You may want to ask more experienced growers but I am pretty sure this is the reason of very slow growth.