As Per My Date I Am 7 Weeks Pregnant But

As per my date I am 7 weeks pregnant but I have a irregular period like 10 -15 later I get my menses, but this time I took a pregnancy test and it was positive....., but when I visited a gyn she said it's a early pergnancy and did a ultrasound and said the gassetion sack looks 4-5 weeks and is irregular go for a bhcg and this report says it's2055 in count ....I am totally showed and scared as to is my baby healthy or no ....and last but not the least there is no heart beat yet as it's just 4 weeks ....Please help me what should I do