Try leaving your kittens outside your bedroom at night, and during the day time close your door to your room. Now if you live in a normal house this shouldn't be a problem as for an apartment this might be a problem, as some apartments might not have doors to the bedroom. Now if you don't have a door to your room and it is wide open or it won't close properly, buy two of those, like, baby proof gate things, to prevent kids to go up or down the stairs and hurt themselves. Stack them one on top of each other and you have a simple way to keep your cats out of your room, this also helps if you want to leave your door open during the day to keep the air curculating through your house/apartment. Cats can still climb them though, so be careful with this choice. Depending on where your litterbox is, being 4 rooms away or 1 you should try moving it closer to your bedroom, if you REALLY want them to sleep with you during the night, you could even put it in your bedroom if you would like. Yes it may stink, but if you keep it clean like you say you do, you'll be fine. Keep your door open if you don't want it in the room though, so that she can actually go out and access it, if you didn't leave the door open and she did her business again on your bed, that is your stupidity. Another thing you could try is going to a Pet Store and buying some books about cats. Now, try everything that I gave you, if none of it works, take a good look at the books again and try to find a solution there. I hate to say it, but if all else fails you might have to get rid of it. Hopefully you were writing this all down and paying good attention. Hope this works.