I think it's common to have moments or even to regularly wonder if you're faking it, especially when you're functional, when the depression or anxiety is in a milder phase or something. That's probably the depression itself talking, the self doubt coming from it and from other sources and society's "voice", because we're still living in a world where mental health issues are always questioned and underestimated when they're seemingly invisible.

Same with the guilt, I think that's pretty common too and again also made worse by society because one of the most common things you get from people is that "others have it worse" or "cheer up, it could be worse" thing, guilt trips meant as encouragements. But there's definitely nothing to feel guilty about, the suffering is real and just because others have it too or maybe have less socio-economic opportunities on paper, doesn't mean you deserve to suffer or that you should be content when something is definitely hurting you, whatever that is.