What could be the reason for delayed periods after protected intercourse?

Hello doctor,

I had intercourse last month, and I missed my period that was supposed to come on the last week of the month. I am almost a month late for my period. While having intercourse, my partner did not ejaculate inside me, but for a few seconds, it was without any protection; after that, we used protection. So there was no chance of ejaculation inside me. But still, I am a month late. I reside in a very cold place, and I was on hormonal homeopathic medication for the whole last month. I do have tender breasts, and they are aching a little. Mood swings also happen, and I am getting cramps in the lower abdomen of my body, but there is no sign of periods yet. I did have a problem with period delays two years ago as well. I was delayed for three months, but at that time, I was not sexually active. I am taking homeopathic medicines such as Pulsatilla and Mensorite, which were prescribed by my doctor. I took two pregnancy tests, but both of them came back negative. I took the tests 21 days after the last sexual intercourse. Could that be a reason for my delayed periods, or should I be worried about pregnancy?

Thank you.