ivf pregnancy

pregnancy still early. i also went to clinic for scan when i test upt n got blur line.tht time around 5w something. at clinic they make a upt test again n got clear line but when scan,still cannot see anything. doc ask me to come again after 2w. after 2w,scan can see the baby wt heartbeats but the size 6w6d,suppose 8w.but doc say,its ok.no prob. this my 2nd pregnancy. the 1st one got different size more than 2w,which smaller.but when its come to 2nd trimester,my bby become bigger n come to it actuall size.