Do I stop here?
'Fermo' — stress the first syllable: 'FER-mo'. The 'r' is a soft Italian trill, not an English 'r'.
Use when you are unsure whether you are standing at the correct boarding point, especially at large interchanges with multiple stops.
'Mi fermo' is a reflexive construction from 'fermarsi' (to stop oneself). In the context of public transport, it means 'do I wait/stop here?' The question form is made simply by raising intonation at the end.
È qui che si prende l'autobus per...?
Is this where you catch the bus for...?
More explicit; add the destination after 'per'.
Questa è la fermata giusta?
Is this the right stop?
'Giusta' (correct/right) makes the uncertainty explicit.
Dove si prende il ventidue?
Where do you catch the 22?
When you know the route number, this is more direct.
Italian bus stops often have multiple poles marked A, B, C for different routes. Always check the pole number against the route map to avoid waiting at the wrong spot.