starting depo next week - questions

so as the caption says, i’m scheduled to start depo next week. the only two people i knew that got it had very different experiences and i was wondering what others had to say. right now i’m on a progesterone only pill because the combined was giving me migraines w aura. i started this back in august and have not stopped bleeding since even though i feel like it’s lightened up a little, will depo make it come back just as hard if not worse? i understand everyone’s bodies adjust differently but i’m just not sure if it’ll get any worse? my bf is very uncomfortable around blood so at this point i’m taking bc for literally no reason and just praying depo stops it. would i be able to get the shot in my leg instead of my arm? is weight gain inevitable? please let me know any and all side effects you’ve had because my doctor gave me none. thank you in advance!!