I haven't got my period yet, my last was between the 19th and 26th December. I'm normally a week later than a month, but I'm now almost two weeks late. I was in hospital during my period and was on a high dosage of antibiotics, some steroids and some painkillers, could this affect my period? This has also caused me to lose some weight but I've put most of it back on now, could this also have an effect? I've messed around but haven't had sex yet.

Yes to all those drugs and situations causing your period to be late, and not be pregnant.