Hey, you'll love it Mite. I loved living on my own, loved going back to my quiet apartment and just being alone, loved eating left over pie for breakfast, but moving in with my guy was the best thing that ever happened to me. Sometimes I get a little riled about his total inability to pick up after himself, but from this I've come to learn what the small unimportant things are, and how to let them go. At night, curled up next to someone else, no matter what shitte has been thrown your way from the world, there is peace. Not to be too shleppy, but living with someone teaches you real intimacy in a way the air plane headed for the zoo never can.
A few days ago, my SO revealed he had used my toothbrush "just a couple of times." I had a brief freak out "What?! Why would you do that?" But then he reasoned that we've shared more than just spit for quite a while. I have this really fancy toothbrush, and he wanted to know how feels, and a few days later a blue repleca of my pink tooth brush showed up in the bathroom.
As for him moving into your apartment, I experienced the reverse, moved into the apartment my guy shared with two other guys who's moved out before my arrival. I felt like I needed to ask permission before I moved things. I have to admit, that apartment never really felt like home and in under a year we moved into a place we found together.
I know you made an effort to give him a space of his own but, it's really, really imporant to redefine the whole space as neutral- not your space that you're allowing him to exist in. A good example of this is how our cats behaved. My SO's apartment included two tiny little girl cats - I'm talk itty-bitty perma-kittens, and I moved in with my cat - slightly larger than average, very muscular. In my SO's apartment the girl cats beat on my cat, cornered him chased him out of every spot he found comfy even though he was twice their combined weight and size. In the apartment we moved to together, all cats were released at the same time. Now in neutral territory, the boy cat plays affectionately with one of the girls, and he even humps her sometimes!