sterilised but period really late help

[mommyof41986]

I am freaking out.
IWas sterilised last august & since then have been having periods as normal ie every 28 days. However, my hubby casuallyasks me if I need any tampons as he was doing a shop for me and its suddenly dawned on me that I havent had a period since 23rd of december so I am 7 weeks late. Only time ive been late other than when pregnant was the week before my wedding which I put down to nerves & stress as it turned up the next day.
im only 28 so I know its not the menopause.
I feel ok apart from a little nausa this last week which I put down to my appetite & I feel really tired but im on co-codamol the last week so it could be that.
I phoned the docs but cant get an appointment til next week & im really scared. A pregnancy is a really bad thing for various reasons.
Can anyone help

It's very rare for a sterilisation to fail.

I don't think it'll help to wait until next week. POAS tomorrow?

POAS? soz im new to this site not quite up on the lingo lol

Pee On A Stick

ie use a pregnancy test.

oh right yeah seems kinda obvious now.
I did a test on monday that didnt develop at all & I could only afford 1 as I dont get hubbys wages til friday.
im gonna phone the docs & speak to them see if the can see me today or tomoz. if not im gunna fo to the gum clinic at the hospital this afternoon.