This does sound a little bit like sleep paralysis. (I've had it for 50 years btw, and am also a former neuro nurse.)
Sleep paralysis is that thing where the brain hormone that normally paralyses all your voluntary movements (but not things like heartbeat and breathing!) during the dream phase of sleep doesn't get turned off till a minute or so after you wake up. Everyone will have an occasional episode once or twice in their life, but about 5% of us get it on a regular basis. It's a perfectly harmless brain glitch, and not an illness.
The reason for saying this is that about half of people who have sleep paralysis hallucinate during episodes. Buffy sees things, I occasionally hear things like running footsteps or banging doors, but my hallucinations are usually tactile - i.e. involving touch. The hallucinations of sleep paralysis can affect any of our five senses, but some of us get what is sometimes referred to as a "sixth-sense hallucination". This is a very strong sense of an invisible presence in the room.
Like Buffy, I'm wondering whether you're having sleep paralysis and failing to notice the paralysis itself. It's usually the first thing people notice, but it sometimes only lasts a few seconds, so I suspect that if the hallucination of a presence is very strong it could distract you from the transient paralysis.
Sleep paralysis tends to run in families - though it has to start somewhere, of course - and the most usual age of onset is 15-25, though it can start at any age. Your comment about worrying about the cleanliness of your house makes me wonder whether you might be older than this. I don't mean to be rude to young people, but they're usually not too bothered about the state of their houses in my experience. And hey - I'm 74 and I think life's too short to spend hours cleaning!
Seriously though, it did strike me as being slightly unusual that this would be your only concern about the perceived presence. Most people are simply terrified when it starts. I suspect it's also quite unusual to perceive the "presence" as someone you know. I've been discussing sleep paralysis on various forums for 20 years now, and I've never heard that one before.
I'm wondering whether perhaps you tend to suffer from anxiety in general. It may be that you find the posts on this thread reassuring, which will in itself reduce the frequency of these attacks. However, if things don't improve, I'd suggest talking about it with your doctor. Once again, sleep paralysis is not an illness that requires treatment, but if anxiety is the problem you can be helped.
Don't hesitate to post again if you have any more questions.