If you got the shot within the first 7 days after the start of your period you should be protected immediately but as you were just after that time your doctor told you to wait 7 days. As you waited 9 days I think you will be safe but if you are worried you can take a pregnancy test , one which gives early results, just to put your mind at rest. No contraceptive is 100% reliable but most give a high protection. The depo shot should give you 12 weeks protection and as long as you go on time for each injection you should be have continuous cover. The number of times you had sex isn't particularly relevant but the timing is. There are only a few days in each month a woman can become pregnant, when she is ovulating, which is why your doctor will recommend the shot within those 7 days after your period. It is highly unlikely you will be ovulating then. Normally it is around 2 weeks before a period. It sounds like you followed all the instructions so it is unlikely you will become pregnant so try not to worry,