I am 5 week 4 days pregnant but blood test is inconclusive?

My last periods were on 11th Nov. and mine is 32 days cycle. I have already missed my periods, and did a home test, which was positive. But my blood test performed on 18th Dec. has been inconclusive. And my doctor has asked me to come again for the blood test after 2 weeks. Can you please help me? I am really worried. As i am having symptoms of pregnancy like swollen , Nausea and headache. Can you please guide me about the reason why my blood test is not coming positive yet?