I was on the depo needle for a year and a half and in this time I always had my period every 3 months when I was due for my next needle. I had my last needle beginning of October 08 and I had my last period 8th of jan , I was due for my next period on 8th of February but I still haven't got them yet. I have all the symptoms of being pregnant ( sore lower back , tiredness , nauseated etc ) but I took a home pregnancy test 4 days ago and it was negative. Could I still be pregnant or is it just the depo needle mucking everything up ?:confused:

It could be either way. Some women fall pregnant very soon after stopping the depo injections, some find it takes many months. Hormonal birth control will cause some women to have irregular cycles for a time when first stopping their use.
See what happens next month. If still no period, try another pregnancy test or you can see your gp about a possible blood test.