I am 8+5 and constantly tired and nauseous although I haven't actually been sick. I told my boss I'm pregnant last week and then called the GP who signed me off for 2 weeks as I feel I can't cope.
In my first pregnancy I just ploughed on at work despite feeling crap, as I was a temporary employee in the middle of applying for a permanent role and didn't want anyone to know about the pregnancy. This time that's not an issue and I just couldn't bear the thought of going to work like this, especially as I've been having a hard time at work recently with low confidence and low motivation.
I do have a 2.5 year old DS so I do still have to do some things round the house but since I've been off work I've spent the last week just flumping around the house in my pyjamas, feeling crap, tired and nauseous, and not really leaving the house. I go to bed early and have naps if I can. I feel like I've got worse, not better, and I'm worried that I'm making the fatigue worse by being 'lazy'... I feel guilty and worried that I'll get so used to lazing round all day that the tiredness will never go away 
I can't bear the thought of going back to work yet though, as I have to get up at 6.30am and be a passenger in a car for a 1 hour bumpy car journey to get to work. (DH and I both work in the same office miles away)
Bleurgh.
Pretty sure the GP will sign me off for another 2 weeks if I ask him as he seemed more than happy to do so. I just don't know what's best anymore 