Why My Period Is Delayed?

pls. i want whether am pregnant or not am suppose 2 c my period dis month on 18th bcux i last saw it July 16th so am 6days late but i still feel as if my period want to come out but if i check it i see nothing & am having early morning sickness which start immediately i wakeup in the morning could it be pregnancy sign? pls i need response as soon as possible thanks.