Well yeah obtaining more sub is very hard, a 100 sub in 7 months isn't bad. Does featured, well they got features, this give so much exposure that they are gonna get way more sub than anyone. To be honest the only way to do better than your comic, well it is to get feature.
But I feel you, seeing other comic getting so much exposure when you work your ass off to get some, and getting almost none, is frustration, but none the less, you have to be humble, like my comics is around 47, it isn't a lot, when I see the other comic with way more sub I am jealous, but I see my friend who just started and only has 5 sub, and think that he deserve more, which makes me think, well 47 isn't bad, I will improve and get more in time, I must not give up :).