From what I've heard:

You planted it two months ago, that's too late in the season. It should be far into the flowering stage now, external plants get higher yields than indoors usually because they are vegging for around 4 months if not more!

Also, 4-5 hours of light a day, is simply not enough, you need about 3 times as much light as that (12-12) once again, this is due to the fact it's late in the year, not much you can do, that's why its growing slow.