Correct Usage Of till/Until

I wanted to ask if the following sentences are grammatically correct:

  1. I was staying in London till a few months back.
  2. I was staying in London up until a few months back.
  3. I stayed in London till a few months back.

Till and until have the same meanings and functions in a sentence. But I don’t know what you meant by saying till a few months back. Did you mean a past few months?

Your sentences are all fine, New Learner-- and welcome to English-test.net. ‘Until’ and ‘till’ are interchangeable in all of your sentences. ‘Till’ is informal.

Can you help me to explain the sentences? Thanks.

Thanks a lot for your replies.
Looking forward to further co-operartion from you.