So I'm finally caught up on part one & two of your Mavins, and this is what I suggest:
Transfer your files to Google Docs. I absolutely love it. It just makes everything easier because it's online and there's an app, plus it checks grammar & spelling.
Describe what's happening, what character's thoughts are & the surroundings. It helps paint a picture for the readers & makes things feel less rushed.
Also, I'd use a few more 'Gavin words' but, I don't think you should spell it 'Micoo' when Michael is addressed.
Take skills from what you've read. Some of the best things I've read are from Tumblr. How did some authors describe and portray things compared to others? Which ones made you feel like you're in the story? If you laugh while writing, people reading will too. The smallest things make me laugh. I was reading one yesterday where Geoff comes in seeing both their faces red and says, "There better not be dicks involved." So Michael puts both hands up and says, "No dicks." I laughed for a solid minute, because with scenes like that I'll put my hands up and imagine how Michael would've done it; hands up, leans back a little & shakes his head.
Lastly, get hyped. That's how I get anything done. It helps me think of ideas, or blow through chapters. Listen to your favorite song, or sometimes I'll literally sit on the floor of my room & recite what's happened so far, and what I have planed out. If you have to, act scenes out so you can get a feel for them & describe them in a way that can be pictured. If Gavin's saying something and is being shy but it's Michael's POV stand in front of a mirror and do it. Think about what Michael would say, and use that to the best of your abilities. Also check out thesaurus.com! If you feel like you use a word too many times type it the box and BAM!
I think you are an amazing writer and need to fine tune your skills. Find out what emotions and types of scenes you're best at then use it to your advantage!
Good luck and best wishes!