Advice needed on who in this situation is the cat's owner

So, I have been searching around trying to find a good place to get some feedback on a cat ownership situation and found this to be as good a place as any.  I am trying to solidify who is the owner of a cat between me and one of my roommates. We are in the process of finding other places to live, and I want to make a claim that the cat is mine.  I would just like some outside insight to the situation.  I am clearly new here, so hopefully this post is in the correct place, but here we go:

One year ago, me, my boyfriend, and a friend decided we were going to live together (each of us with our own rooms and share of the lease).  We all then agreed we would look into adopting a cat.  Before we ever went to the shelter however, we agreed that one of us needs to be the one responsible for the cat (to be primary caregiver, have responsibility, then take the cat whenever we move out).  The friend was the one decided on to have this responsibility given my uncertainty and my boyfriend simply not wanting to deal with the sole responsibility.  Once this was decided, the friend refused to go to the shelter to help pick out the cat (me, my boyfriend and a different friend actually picked the cat out).  We actually had to force him to come the day we adopted the cat so all of our names would be on the adoption papers.  Then, when we signed the papers, I signed as the primary contact and then the friend signed as an alternate contact.  So, now I'll just list out the things I've done for the cat this past year and things that might signify me or him as the owner:

1.  Decided as roommates that friend would be responsible for the cat and keep the cat

2.  All three of us signed the adoption paper, but I am listed as primary contact with the friend as secondary

3.  AKC microchip tag for the cat is in my name

4.  I took her to the vet when her shots were due and paid for the visit and registered her with the vet in my name

5. I purchase and apply her monthly flee medication and trim her claws

6.  All three of us equally share food, litter, adoption, and pet fee costs

7.  All three of us keep her fed and clean her litterbox, though the friend tries to vastly overfeed her

8.  The friend never plays with her even though he never leaves the apartment.  He has bought her multiple toys, but never uses them.  My boyfriend and I are the ones who play with her (she is VERY energetic and needs daily attention), pet her and give her love on a daily basis.  Whenever he leaves his room he will occasionally reach down and pat her head a couple times before walking away, but that's the most he will do other than trying to lure her into his room, which is another point.  This cat visibly would rather be around me and my boyfriend.  She waits for either of us to come home, even though the friend is always there.  He will lure her into his room with the toys he bought by waving them around, then once she's in, he stops, and she goes to hide under his bed.  He does seem to like her and by no means abuses her or anything, he just seems to have zero regard for her needs.

Within the next three months, I will be moving out to likely live on my own (pending where I take a job), my boyfriend will be moving in with other friends, and I do not know where the friend will be going.  Given that my name is on the adoption paper and the microchip as the primary contact and that I paid her vet bills, I see myself as the owner, but I do want outsider opinions.  Before we adopted this cat, we did agree that the friend would be responsible for and the owner of the cat.  So is he the owner given this promise, or am I the owner given the documentation and everything listed above?

I hope everything here makes sense.  Any insight will be appreciated!

Sounds like the cat is yours - adoption papers and chip are under your name and you do most of the work anyway. Unless the roomie is really fighting to take the cat with them, you may as well go ahead and lay claim with documents in hand.

My boyfriend's cat's adoption papers and chip are in his ex's name, but he's had the cat since they went their separate ways several years ago. Unless there's a disagreement as to whose cat she is, the one who wants and will care for her is who I'd consider the owner.

This is why verbal agreements are generally unenforceable.  He said/she said arguments rarely go anywhere good.  Documentation usually takes precedence.

I say let the cat choose. Sit on opposite ends of a big room, put cat in the middle, watch where cat walks to. Repeat for scientific accuracy.

I agree with pinkdagger- your name is first on the adoption papers, on the microchip, and the vet records. I think all of this, especially vet records and proof of payment to the vet, makes the cat legally yours. Also, if your name is on a rabies vaccination certificate, that is also proof of ownership.

When you, your friend, and your boyfriend move out, the person who takes the cat will be the owner.

That saying "possession is 9/10 of the law" may not be an actual law, but it will be difficult, if not impossible, to get the cat back from the person who takes off with her. 

If your friend takes her, he will just start new papers with a new vet with his name on them. Short of kidnapping, you will not be able to get the cat back. But if you take her, you have a very strong argument for ownership, since you have taken care of her all along.

You don't say if the friend even wants to take the cat - is sounds like you are just trying to figure out who legally owns the cat. If that's the case, I hope you can work it out with your friend. If you can't come to an agreement and there are hostile feelings between you guys, I would move the cat to a trusted friend's house a week or so before moving out. 

Because, bottom line, the person who moves with the cat is going to get to keep the cat. Good luck, it sounds like the kitty is much better off with you, I hope you work it out.