Bitterness, Or Just Feeling Constantly Left Out?

I hate being the bitter cynical bitchy person who ruins other people's conversations (the whole 'can't talk about that around <insert minority group/person here>) but you have no idea just how frequently things crop up in casual conversation that stops me from talking because I either just have no way of relating to what people are talking about or me attempting to would make other people uncomfortable. Or possibly result in me getting pissy at people, or me trying to not be pissy at them and them taking it as such anyway. So I stay quiet. And then people are all 'why are you so quiet?'

Okay so most of these people may not know about my problems, because I don't like constantly talking about them and having to explain about them. But everyone everywhere, both on the internet and in real life, inevitably winds up talking about things that I can't join in with and inadvertently insulting me. Not intentionally, but I feel bad when people are whining that they feel bad because they've spent all day sitting on their ass playing video games and only done half of their chores, when their list of chores that they've done is about four times what I can handle on a good day and I've done virtually nothing. Except sit on my ass half-assedly playing video games because I can't even play them properly.

Or when someone asks what they've got planned for the weekend and they reply by rattling off a huge (in my eyes) list of things, then round it up by saying 'not much actually, pretty slow weekend'

Or when they're talking about their jobs and how they moved from an office job into waitressing because it got them more exercise and they hated sitting on their asses all day.

Or when they're talking about uni and how hard it is. And then talking about how it's awesome and they just get drunk all the time. I think there might be some sort of correlation there.

Or when they're discussing exercise.

Or when they're discussing diets and 'healthy food'. (I'm meant to eat 10g of salt a day. I have problems with low blood pressure and low blood sugar. I basically need to eat junk.)

Or when they're discussing expensive things.

Or when they're whining about being 'poor' and therefore can't afford said expensive things. After buying said expensive things. 'I really shouldn't have but I just couldn't stop myself!'

Or when they're whining about how they can't write because they can't concentrate.

Or when they whine that they're in pain and I offer them painkillers and they're all 'it's not that bad, I'll just grin and bear it' (Hint: If it's not that bad, don't whine. If it's whine-worthy then it should be painkiller-worthy. Otherwise it comes off as you don't actually want to fix it, you just want sympathy.)

Or when they whine about 'insomnia', and I sympathise, and they say it only happens to them when they've had too much caffeine etc and start trying to tell me about good sleep hygiene to cure my insomnia. (Hint: That's not fucking insomnia. That's poor sleep hygiene. Big difference. Main difference being that good sleep hygiene will cure your bad sleep hygiene woes.)

(NB: These are all just examples from today. Many, many more happen on a daily basis. I don't usually write them down, I usually just sit there quietly waiting for it to get back to a topic I can actually talk about. But I am so bored right now.)