Could I be pregnant?

Hello everyone.
I am 18 years old sexually active. I live with my husband in Chile.
Been my only partner.
So my last period was on September 1st. Lasted about 4-5 days, as usual . So for my next period I was expecting it around October 1st , but instead I got some really dark brown discharge that had spotting , kinda pinkish. This lasted about 3 days and the blood was very light, and I would only see it when I would wipe . I only needed to wear a liner for the brown discharge . On the 4th day of my missed period , me and my husband were really sick, throwing up and diarrhea , so I decided to go to a  gynecologist . He told me that there was a change I was pregnant , and sent me to get a blood test done. It came back negative. Maybe 4 days was too soon ? But I hear that blood tests don't lie ?
Now it's been 30 days late and no period. My only symptom I would say is my boobs are sore, and my nipples have been itchy .
I'm never really on time with period but I've never been this late?!
I havent tested again because Im just tired of everyone saying im not pregnant.
I have doubts because according to MyMonthlyCycles I had sex on my ovulation day. Always unprotected. Im not on birth control or anything like that, so chances are very high, but once again according to other people blood tests dont liee!
Any ideas ? thanks !

[RockRose]

I think chances are pretty good that you're pregnant,  and since your periods are irregular you might not have been far enough along to test pregnant when you had the blood test.