My Age Is 33, My Height Is Approximately 1.73m And

My age is 33, my height is approximately 1.73m and my weight is approximately 96kg. I am currently using Petogen injection for prevention and i was supposed to go for my injection on 31 March 2016 but missed it so its been about 2 weeks since i was supposed to have the injection. If i have the injection today should i have a pregnancy test first? And also what can i do regarding my weight?