Menstrual like cramps are very normal during first few weeks of pregnancy as your body is trying to stop cycle and stretching to make way for baby.. unless you start bleeding and cramps become very severe with back pain, you have pain on one side only, blurry vision etc.. then you should go to ER straight away..
regarding symptoms every women and every pregnancy is different.... give it a time you probably going to get hit by symptoms later in pregnancy.. i had no symptoms apart from boobs hurting till 5-6 wks and i was glad but i was hit by nausea so bad after that and it stayed with me till 10wks.. and i still use to come till 20wks...
Very normal! Your body is building up and stopping your period. Its also normal to experience some implantation bleeding too :) congrats on your pregnancy