Hi kelly, no i don't think your pregnant,as you say the test was negative.
Your minds just saying......missed a period = pregnant.
The trouble with the contraceptive pill, is that after a while it can sometimes mess up your monthly cycle.
O.k yes there is a slight possibility that you could be pregnant, nothing is 100% safe, but it's highly unlikely.
You've been on it for a year now, which is quite a long time, it may be that you need to come off of it for a while to re-regulate your periods, which some doctors do suggest,others may simply say you need a change of contraceptive pill, to bring things back to normal.
Quite often people who do take the pill, will on occasion miss a period,but then have one next time round...... so don't worry