Could I be pregnant?

Well for one my period is 6 days late (my cycle is around 17-20 days long and my last 'period' was on the 2nd) i did have unprotected sex on the 27th August, but like I said I did get a very light period. Currently I feel like I have a terrible cold, I'm frequently suffering with nausea and feel bloated most of the time. 
​just wanted to know people's thoughts,opinions etc before I even consider taking a test. 
​Thanks in advance guys! :-)