ITR filing for new proprietorship firm (I am freelancer) with less than 2.5 lakh annual income.

Hi,
I am a freelancer and registered a new proprietorship (Micro enterprise) firm under UDYAM registration portal. What nil returns (ITR 1 or 3 or 4) the owner should file when annual income is less than 2.5 lakh rupees? I used to file ITR 1 the previous years.Also is export of service to be shown in when filing ITR? (Clients are physically located outside India and I am physically located inside India for past few years).

Regards,
Kishwar