Yes - that was my point, I think there are two readings to the sentence, but yours only became apparent to me after I read your translation.
This is how I understand the English sentence, rather than "This is how I am thought to be". But grammar point taken - Is mar seo ba cheart dom a bheith.
Ah, ok, I've just realised how you got your translation Quevenois. So in English, 'suppose' does have the meaning of 'think'/'believe', but this changes in the passive voice (similar to the verb 'mean'), so:
"I suppose...." = "I think/believe...."
"I am supposed to..." = "I should...."
"it means..." = "it signifies..."
"it is meant to..." = "it should..../"it is supposed to...")
So "This is how I'm supposed to be" = "This is how I'm meant to be/ This is how I should be"
The British Isles are awesome - I know, I live there - but Ireland is not a part of them. K thnx bai!
Labharfainn níos mó faoi, dá dtuigfinn an bhrí...