The nurses are absolutely right!  I'm part way through chemo, having had 4xEC and about to start on 4x paclitaxel.  It's been a bit like pregnancy for me too.  I've suffered from nausea and sickness, although the worst of it was solved with new medication after my first cycle (so definitely tell your medical team about difficult side effects as they can usually prescribe something to help).  There have been times I've had to keep nibbling to get rid of either nausea or a horrible empty feeling in my stomach. And my taste has been all over the place - eg. I can no longer drink tea or coffee, and I hate the taste of water.  
 

So I agree that you should eat what you feel like, and that might well change from one cycle to the next (hence good advice from ProfBaw not to stockpile).  I can no longer face some of the food I ate lots of after my first couple of cycles - I don't even want to see it in the fridge.  I do try to have some healthy food in the house (eg. Veg soups, smoothies, dried fruit) so that when I'm hungy I don't always resort to sweets and crisps.  I also try to get out for a walk most days to get some exercise  But although many people are lucky and don't suffer bad side effects, for lots of us getting through chemo is challenging enough without having to worry too much about diet.  So I'd say don't go mad and live on chocolate, but in general take the nurses' advice, go with the flow, and eat what you feel like eating.