Each pregnancy is totally different...
I am currently on my 24th week of #4. :-)
My 1st (2001)(girl) No nausea, nothing more than just tiredness and sore boobs. Went over due by 2 weeks and had to be induced..8lbs 3 oz
My 2nd (boy- 2004) No nausea, tired, achey, ligament pain... Over due by 2 weeks and induced, easy delivery 9lb 7oz
My 3rd (boy- 2007) No nausea, tired, achey, ligament pain, itchy legs, cravings... Over due by 2 weeks and induced 10 lbs.
This one. (girl due end of april) ugh... nausea, indigestion feeling, tired constantly, possible gallbladder issues causing intense pain attacks. I have been feeling the nausea for the whole pregnancy although I have not thrown up at all. Oh, and the gassy feeling. lol
Each baby causes your body to react differently. It varies on the amount of time your body is given to heal after subsequient births also. You seem to be stacking them pretty close. :-) But that may have nothing to do with it.
Each pregnancy you experience you will notice more of the "symptoms". One factor could be that you yourself are ageing and your not as able to rest yourself because of caring for the other munchkins and life. Make sure you are taking your vitamins so you can combat any deficiencys...
My moms hardest pregnancy was her 5th (and last)... And even though this one has been my "hardest" the things I am experiencing are not out of the realm of normal... Well, except for the pain part... But it could be worse!!
I have found that I HAVE to eat every 2 hours to keep some of that icky feeling at bay. Also chewing on some calcium tums helps wonders also!!!