Self harming/Abusing yourself -or someone else (MBP)- for attention can be a symptom of many disorders. Or none at all. It's "just" a behavior. Like isolating is a symptom or behavior. Taken purely on their own, neither is enough to even begin to diagnose FD/MBP or PTSD.
...no first of all I really do suffer from self harm urges, depression, and PTSD.... so how could this be manchausen?
There are 2/4 forms of Munhausens / Factious Disorder. Abusing yourself or someone else for attention is one form, faking it is another form.
People tend to think that Munchausens is faking it/lying, and Munchausens by Proxy is actual abuse... but that's wrong / only half the story. Some parents never abuse their children, they "just" lie about "what's happening" with their children for attention; and some people never lie or fake it for a moment, but are very much abusing themselves for attention.
As I said above to Uzo, though, that's just a behavior... And it can be a part of a LOT of different disorders. For different reasons. With PTSD it's
more likely to be a form of trauma reenactment (abusing yourself now, for the attention you didn't get during your abuse back then), but that's not the only possibility by a long shot! Similarly? When you look at the same behavior under the lens of other disorders (Borderline, GAD, Major Depression, PPD, Anorexia, Munchausen by Proxy, etc.) there will be other other reasons it's there/being used, as well as other ways to treat it.
Which also means I very strongly urge you to discuss it with your therapist. Whether it's trauma reenactment, or something completely different, it's a challenge you're struggling with. And that's what therapists are there, for! To help you with challenges you're struggling with.
Hint : I would ALSO bring up your fear of mentioning it, because being afraid that someone will stop being nice to you when you need help is as big a deal as being willing to hurt yourself so someone will be nice to you.