From last few days, my tummy size got increased drastically.

Hello,

I m 27 year old girl, and my body structure is slim from the first. But from last 2-4 months , I see that my tummy is size increased too much. It's not much big for others but as per my body structure I don't feel it proper. What can be cause/reason of this sudden change in my structure?

Can finguring be one reason of it? I have 2-3 times have done finguring myself. Can it effect to my tummy?

I work in office from last 4 years so I don't think so that whole day sitting position can be cause because it would the cause then I should got big tummy before 2-3 years.