I was sexually assaulted and it doesn’t sound believable

I’m a 23M who lives in Australia. I was sexually assaulted in a bathroom in a shopping centre. I walked into the bathroom when two men and a woman followed me in. One of the men punched me in the side of the head and then proceeded to push me headfirst into a disabled stall. The other two followed suit. They held me against the wall and took off my pants. She started to suck on my penis. I involuntarily got hard. The two men then stepped on the back of my legs to get me down to my knees so she could rape me. She didn’t stop until I finished. She got off me and then I was kicked in the side of the head and woke up minutes later. Despite having noticeable bruising, the police didn’t believe I was sexually assaulted, and I’m worried my gf would also think the same.