Hi Jasmine,
Sorry for your disappointment. But don't worry, it will happen one day. Regarding your question, usually it is suggested that you can do home pregnancy test sometime five days early before your periods due date or the day after you missed your period. But still it is recommended to get a blood test done from the doctor for conformation. You didn't do any home pregnancy test so you don't really know if you were actually pregnant or not. My periods are also very irruglar, sometime 23 days cycle and sometime 35 days cycle. Periods usually get delays due to stress, harmonal change or some time it could be chemical pregnancy. Which lots of time women don't even know that she is pregnant.
I would suggest you to check with the doctor, I have read on some sites that sometime women still get light periods even when she is pregnant. So, better to check with the doctor and ease your mind. Good luck.