Hey Brino!
I just checked out your Luckiest Water Bottle Trick Shot video and I thought it was great! Then I looked at your tags and they weren't so great. Your only tag that is ranked is your channel name. I think your other tags would rank if you added your video title in your description. You usually want the very first sentence in your description to be your title and then the following ones to be information about your video. Then for your tags you will obviously use one with your full title, and variations of it. For instance Luckiest water bottle trick shots, impossible water bottle flips and other variations of that you usually want to do around 3 or 4 words for your tags.
I don't really know how to get more subscribers I'm in the same boat as you are there, I just saw a movie on improving your tags etc with the new algorithm and since your content is good you'll get more subs in the process. Hope this helps!
Fully