Since then I have my business.
I know we can use (since) only with present perfect, but this sentence is simple present. Is it correct at all? Maybe in iformal English?
And is this question (Is it correct at all?) correct? I mean is it correct to use at all at the end of a question?
Certainly.Is it correct to use 'at all' at the end of a question?
'Is there no bread left at all?'
'Have you any questions at all?'