BWMum,
Just noticed you'd not had a reply yet - which isn't on, so...
I'm no expert but would point out a few things:
1: Your body is going through something HUGE. It's completely natural to feel tired and emotional all the time - ESPECIALLY if you're feeling sick a lot. Be kind to yourself - don't expect too much of your poor body and try not to feel bad about feeling bad, IFYSWIM...
2: It is, however, worth going to to your GP or midwife and geting both your iron levels and your anaemia levels checked out, as both these things are common in pregnancy and can make you feel rotten. Describe your symptoms, take a sample and get them to give you a full once-over. These things can crop up at any time, and are relatively easily solved once diagnosed. It may be more than general pregnancy knackaredness
3: Bollocks to work, frankly. You're pregnant, and doing far more than can reasonably be expected. Any employer with half a brain will realise you're not being slack, neither have you suddenly lost your ability to do your job. You are simply pregnant and struggling a bit. 'Most of your colleagues' are not pregnant (I assume!?) and therefore comparing yourself to them, work-wise is unfair on yourself. Most of them wouldn't be coping half as well as you are in your position, I bet.
Give yourself a break. Do what you can. When you feel tired, GO HOME, and don't feel guilty about it. It just simply isn't important enough in the scheme of things to upset yourself about. I'm now 33 weeks, have a similarly stressful job, where long hours are the norm and have now decided to stop beating myself about what I'm NOT doing, and congratulate myself on the amount I am getting done.
Anyway, that's my two-penn'th. I'm sure there are many more on here more expert than I am who can give you some more useful advice...
Mine is really simply - be kind to yourself - you deserve it...
Big hug - hope you start to feel a bit better soon...
DB
xx