Delayed periods. Is my period delayed?

I have had irregular periods since the beginning. Since 2 years, they have been a bit regular, but I have still missed 1-2 months after each 3-4 months. My cycle is around 35 days. I recently lost my virginity. We had protected sex everytime, and he never finished inside me( just in case the condom broke). It was in the beginning of November, when I was not ovulating. Before that, I got my period on 3rd October, and now have a delayed period this month. I was also diagnosed with initial stage psoriasis, and am taking homeopathic medication for the same, since beginning of October. I haven't been under a lot of stress, but my sleep cycle is disturbed. I get around 5-7 hours daily, sometimes even lesser. My at home pregnancy test showed negative. Is there any chance that I could be pregnant? If no, why is my period delayed?