Is pregnancy still a possibility?

[getsomewhere]

According to my period tracker I was the most fertile from October 14th- October 21st with my date ovulation being October 19th. I had unprotected sex from the 18th-28th. My boyfriend came inside me on the 18th.
I am on no form of birth control and have had irregular periods up until the past August when I started a progesterone regime.
According to my period tracker my period was due on the 1st of November. Now, almost being the 5th--no period.
I took a pregnancy test on the 29th and it came up negative. I took one today (11-4) and that was also negative.
I've been feeling bloated, nauseous during midday, and crampy on the 2nd of November, and VERY VERY tired. Other than that, I feel fine.
I just got back from a business trip on the other side of the world, so I am not sure if that is what is making me so tired, but I do these trips frequently and can get back to a normal schedule after 1 day...it's been 5 days.
I also was diagnosed with strep throat on the 30th of October, but feel fine as far as that goes.
So, is it possible that I could be pregnant despite the negative tests? Should I go in for a blood test?

 

[BunInTheBelly]

Totally still possible! This site has results of pregnancy tests taken by pregnant women listed by DPO. All the women who contributed to the study were actually pregnant on this cycle, but some were still getting negative results.

At 17 DPO, 12% of pregnant women were still getting negative tests. So I'd say you definitely have a chance at still being pregnant. Fingers crossed!