To the OP I know exactly how you feel, I started in January this year, and I'm at 37 subs, YES I am very happy with subscribers I currently have, but feel like I could be doing a lot better, I too compare myself to a lot of other channels. I also get very annoyed when I see people posting things like "I have 200 subs in 2 weeks of youtube, what am I doing wrong?" "I used to average 1,000 views on youtube now im only at 500 what should I do?" Just makes me angry!
I do like the advice you are being given, yes its always good to be patient, never give up, etc. and Sir Derpington is right on the dot, I wouldn't suggest Bioshock Infinite though, I mean its a new game so I would assume there are tons and tons of other channels doing a LP and not to mention some big youtubers as well (Cryaotic and CinnamonToastKen to name a few). But other that you got to give your viewers a reason to want to watch your videos. I bet I could type any game you've played on your channel (havent looked at your channel atm.) and find 5 (or more) other channels of people playing that same game. Whats going to make me want to watch you instead of someone else?
Try to stand out with your personality, through commentary, maybe you're funny, maybe I could like the way you act out character dialogue, maybe I like the moral decisions you choose, or maybe I just like how you play a game, or explain a story.
And yes, variation can widen your audience a bit, maybe try to stick to one genre but it is definitely up to you and how you want your channel to be represented. I would recommend just 2 different series at time and alternating between them each day, 3 is too much as I am finding out. Some of your subscribers that are there for a particular game have to wait longer for a new episode.
Hope I and the YT community were able to help you out, I don't think you should quit on your channel, don't let it stress you out, just have fun with the games you play.
Oh yeah, one last tip that really helps is collab with other youtubers, play co-op games together or just co-commentate, best way to get new subscribers and make friends!