Recently, ok more of like the past 6 months i've experienced this annoying habit from my cat.
She pees in my bed when I'm not home, or simply when I'm not looking. Like 2 months ago, she would pee several times on one day for a few consecutive days. I had a soft comforter, not down. along with sheets and a mattress. The comforter was dark brown so I couldn't tell right away that they/she had peed on my bed. but at night I just started smelling it. it was like in the middle, a little lower, to where my knees might be or so. that happened several times again, of course I changed comforters, cleaned as I could. I bought a plastic mattress cover, put new comforters, and it happened again. To the point where I had to buy a new bed. a futon to be exact. the FIRST day after I had slept in it, meaning the next morning, or day, I don't know how or when but the Futon was already peed on. I went to the store to buy "Nature's Miracle", and another plastic mattress cover. since I don't have the money to be going to the laundry to wash all my comforters all the time, I simply would leave the futon with the plastic cover on, but no comforters. And it was peed on.

Only 10 minutes after I leave the room, I come back and the Futon has been peed on. Several times a day , for a a couple of days. Oh and several spots on the floor.
All this time she had the kitty litter box in the same spot. the same product always.
So I decided to clean my carpet fully, with soap and a brush. change my room around, wash all of my comforters, leave the futon in bed position, of course with just the plastic cover on. no peeing on my bed for like 1 1/2 months. Like 3 days ago, at night I start smelling that god awful smell. It's right in the middle of my bed, by my chest/upper back. I was home all day. In my room. And didn't even notice when that happened. But it happened. Again she had the same kitty litter product. I changed it to just a mattress pad, of course with the plastic mattress cover under it. It lasted I dont know a week, and the mattress pad got peed on. That day I had gone for a short while, and when i got back I saw that bad yellow spot, and just got mad. I grabbed the mattress pad and put it in the washer, because it's small. So i can wash that. anyways today I got called in to work, I worked about 10 hours, got back home, and the spot was there again. actually there was several. not just one. But today the only difference was that I changed the kitty litter because it's natural, and it doesn't stink. or pretty much I wanted to change because the other one wouldn't cover the smell.

I am getting really tired of this. I love those cats dearly, but I am not rich enough or have the patience to be washing my comforters and sheets every day. It's 12:30am right now and to be finding this mess in my bed when i just want to rest after working 10 hours is really aggravating.

Please someone tell me what I can dooooooo to make this stop!

Oh and hmm from the usual information I have found on google searches, no there is no new cats, or no new people living here. Just the usual me and my cats. I live with my parents but they never go in my room. I let the cats out once in a while, but not all the time, because I have been told by my parents that the cats, not sure which one, peed on the sofas, they are leather, but they had fleece blankets on them.

Please help me, And I'll be happy to tell more information if you need it. Thanks.

The first thing I'd do is take the cat to the vet for a check-up. There might be something medically wrong.

Then look at the litter box carefully. The only time my cat peed on my bed was when I let the level of litter in the box get too low. I was going to change out the entire box the following day, so I didn't add new litter in. And she let me know that was unacceptable.

Could one cat be intimidating the other from getting into the litter box? I had this problem once. It wasn't a matter of the one cat getting in the other cat's way or hissing at her or physically blocking her from the box. She would just lounge in the general area of the bathroom door (the box was in the bathroom) and the other cat was afraid to pass her by. They got along great otherwise. Adding a litter box at the other end of the apartment solved that problem--the "mean" cat couldn't block all the boxes at once.

If you have two cats sharing one litter box, you might need to clean it out more often, say two or three times a day instead of just once. Cats can be finicky.

You could try using the "Cat Attract" litter.

Have the cats been spayed? Also, what is your mood when you're around the cats? If you're agitated from the cat's urinary problems then this will just add to the cat's stress level. If she's already ill, stress is the last thing she needs.
Do they have plenty of things to play with and do they have a window to look out for a change of scenery? I can see where they may get a little stir crazy being kept in a bedroom, but I think there's something going on, either medically or environmentally, for your cat to start this behavior.

Until you have her checked out and make some changes, I'd leave the bed covered with the plastic cover and place all your bedding outside the room when you're gone. Make sure you're treating the bedding with Nature's Miracle since soap and water won't remove the odor.....maybe it does for your nose, but she'll still be able to smell it.