Hi, I am pregnant again...for the 7th time, 5 m/c's and 1 healthy DD! Some of my pregnancies have had nausea, others had nothing and with my 1 successful pregnancy, I was throwing up until week 26 and couple of times in the hospital. I think they say that morning sickness is the reaction of your body to the hcg rising, so it could be a good sign!
I read somewhere that the fact that you are feeling sick is a good sign. Not necessarily that it'll be a viable pregnancy but it shows that your body is high in hormones that are good for you and the baby. Not so comforting when you are puking though! I had 18 weeks of terrible morning sickness with my daughter and I had to keep telling myself that the worse I felt, the better my baby was doing.
Symptoms are not an indicator of whether or not the pregnancy will be viable. I had no symptoms my last pregnancy and miscarried at almost 10 weeks. Ive had no symptoms this pregnancy and am now 27 weeks with a healthy baby :) I think it's all in how your body handles the hormones. Every pregnancy is different!