juicy my GP said much the same as fairy's about fluctuating symptoms. But it is so hard when we are focussing so closely on our bodies and trying to read the runes in each tiny change or twinge. I am not the best source on early pregnancy symptoms, though, as mine have been pretty uniformly unimpressive to date (11 weeks now, so yes I still remember!)
On a slightly different note, I know your betas have been high so you may be cheered by some research which I read at 5 weeks and gained, ooh, a couple of hours reassurance from :-)
Www.mycoyfertility.com/rbonline1.PDF
This looks at day 14 betas as a prognostic indicator of viable pregnancy. Obviously not something you want to read if your betas are low (been there after my first cycle and the embryo only stayed with us a few days), but working backwards from your high day 18 results, I guess your day 14 beta would have been well over 300 ie off the top end of the scale. According to the research, those levels give you really great odds of a viable pregnancy, as well as a 60% probability it's twins... My beta at day 14 post national EC was well over 200 (with definitely only one in there as I only had a single frozen blastocyst transferred) and I know I found the encouraging stats temporarily helped me manage my insanity. (At least until I hit 6 weeks, still wasn't sick and started spotting, but that's another issue :-) .) Of course, statistics like these are only of limited help to us when we have become accustomed always to being in the small percentages ourselves and our BFPs against-the-odds are testament to that. But it might be a comforting and hopeful thought for 5 minutes or so :-)
fairy fully understand and your commitment and professionalism are a credit to you. I am a small cog in a big wheel myself (though will still worry about my files, because I care). But my DH works for a small third sector organisation so I can imagine how much harder it is for you in a small company. I think at some point though, you have got to wrestle your conscience into a box, sit on the lid hard, and put yourself and the little one first. It sounds as though you are doing all you should and can to prepare for maternity leave with your work left in good order, and I guess keeping the issue of training and hand over on the radar is the best you can do now. You sound a great employee and colleague, I hope they value you accordingly!