Hi and welcome to the forum! I am glad that I can help you.
You want to know a little bit more about transmission of HIV.
HIV (human immune deficiency virus) causes weakening of the immune system. It can be transmitted by direct contact of blood flow with bodily fluids such as blood, semen, pre-ejaculate, vaginal fluid and breast milk. The possible ways of transmission of HIV are unprotected sexual intercourse, transfusions (or medical procedures that cause bleeding), and from mother to child (vertical transmission).
According to the data that you dscribed, you suspect that you might be at risk of being infected with HIV. Contact with blood by sharing needles may cause transmission of HIV, HBV, HCV or HDV (the last three are viruses that cause hepatitis). If the person is infected with one of these viruses, anyone who shares the same needle (which is highly not recommended) may be infected with the viruses. To be completely sure, get yourself tested for possible HIV infection.
Please keep in mind that I provide medical information only. I am not able to diagnose medical conditions online. Please contact your doctor for further advice and information about diagnosis of possible HIV infection.