Could I be pregnant?

Circumstances, I believe, took place between September 27th - October 10th. 
I was given oral sex by a guy on the day I thought my period had finished (September 27th), except I ended up bleeding out on the bed sheets. A night or two later I went to the hospital after contracting a UTI but the medication didn't work. I then went to my local family planning clinic and was prescibed medication that provided instant relief. Within two days the same guy and I had sexual intercourse without a condom and he pulled out before ejaculating. The next morning he realised I had thrush like symptoms but they soon subsided. (We had intercourse once more a few days later but a condom was used). 
After a few more days the guy and I ceased contact and I decided to have an STI check as my vaginal discharge was thicker than usual and emitted a horrible odour - which is very unusual for me. I also later found out he had a past case of chlamydia. The Doctor took the swab and considered I may have bacterial vaginosis and prescribed me with the usual 5 day medication which I completed in full. 
A bit of history about myself:
Height: 168cm
Weight: 47.2kg 
BMI - Underweight 
The fortnight I spent around this guy revolving around copious amounts of drinking/smoking and I can't honestly remember eating anything apart from a few chips/dip and a fish sandwich. Early October I was also hit with a bout of anxiety/depression. 
My period is between 3-5 days late and I'm not sure if I could be pregnant or the amounts of stress, infections, antibiotics, excessive alcohol consumption, and lack of food I've put my body through have severely delayed my menstrual cycle. My period is regular around 16th-20th of every month. 
I'm not experiencing any notable symptoms.