Does anyone else have this huge fear of being some sort of pathological liar when it comes to your mental illness (or other things, but only mental illness in my case)?

I'm incredibly worried about faking/exaggerating/lying about my symptoms. I mean, what if I'm actually delusional? What if I'm lying? What if I'm so good at lying I've managed to convince myself and the professionals that I have certain diagnoses when I'm actually "healthy"? What if I'm making everything up? What if I'm imagining everything? What if I'm making everything up to get attention? The fact that I, after years and years of handling everything on my own, finally get some attention and think that's a good thing really doesn't help with the anxiety. What if I want to feel this way? Is it possible to fake 10+ years of mental illness? What's the truth?

The weird thing is that I'm a very honest person. Ask my parents and they'll tell you I never, not once, broke one single rule while growing up and I still think rules (at least most of them) are to be followed. People often tell me I'm one of the most honest people they've ever met. Truth is very important to me.

The fear of being a pathological liar isn't as bad nowadays as it was about a year ago but it still plagues me. A year ago it was really bad. I'm not sure I can even explain how many hours/days/weeks/months I spent in my room going through conversations and memories in my head over and over and over again to make sure I had told no lies and that I hadn't been faking my symptoms. The whole thing gave me such anxiety I literally hit my head sometimes to try to make it go away. It's still like that (though not as much). I finally told my psychologist/therapist about it yesterday and he said it's my OCD that's forcing me to do these things (what if I don't have OCD? What if I'm just faking it?). Talking about it was the first time I felt like we were actually on to something in therapy. I think my therapist noticed how important it was too because he made another appointment for Thursday this week (two days after last seeing him) and said he wanted to talk more about all of this.

I'm worried. What if he misunderstood what I told him? What if he doesn't get it? What if he'll think I'm really weird/crazy/attention seeking when I tell him that I sometimes think attention is nice? What if I'm lying all the time? What if I'm exaggerating everything? What if I'm lying right now as well?

Can anyone relate to this?