this is an important shaila and requires a long response. i will be as breif as possible.
if you are sitting on your bed doing something of importance, for instance writing, you can stay for longer. if you are sitting on the bed cecause of the comfort it provides, you may have to shorten the time you spend on it. texting/emailing freinds is not considered important, but for business it is ok. if you get a call from a friend and you might stay on the phone for long, you must get off of the bed.
as for the toilet, okay here it gets complicated.
if, in your bathroom you have magazines that you MIGHT read. you can stay for 2-3 minutes max. for magazines you WILL read 1-2 mins max.
if you have no magazines, you can stay as long as you need to with out being too comfortable.
as i said before, this is a complicated issue and you should ask your local rabbi