I think it's after 100 videos not subscribers but I'm not sure
as for the growth from my own personal experience I mostly got subs thanks to Twitter and meeting Youtube friends, I have 1,360 subs right now but I can tell you that not all of them are active watchers. I took a look at your channel and you have videos with 500 views which is amazing, people struggle with views more than subs trust me. And don't ever give up on your goals, this sounds cliche but if you truly want to be successful in Youtube then keep working on it, it's just like losing weight, sometimes you want to give up because you can't get rid of that small part of belly fat but if you don't give up and work harder you'll achieve your goals. Life works just like that, if you work hard on something you'll get it sooner or later but you will get it
I truly wish you all the best