That someone can be 4-5 months pregnant without knowing?

Before you get all offensive

The females in my family tend to bleed the first couple months of pregnancy, don't ask idk why. I had a positive test then ended up bleeding. My boobs been killing me a lot! I'm now all stuffy. Heartburn like a mofo. The only thing is I haven't really gained any weight so I know there's a HUGE possibility of I'm just overthinking this and making it like I am cause how badly I want it.