Gained 2 kgs but clothes fit fine just as before....what can be the reason?

[mumof2kiddos]

Till January 2016 I was hovering between 57 to 58 kgs but nowadays I hover between 60 and 61 kgs. However my clothes have remained the same, they dont feel any tighter and I can wear the same size clothes with equal ease as before.
Am I fooling myself or it can really happen? How much do you have to gain to go up by a size? I was 72 kg size 18 in Dec 2013 and 58 kg by Dec 2014 size 10/12 and still the same dress size now (some 12 sizes are big and some fit nicely). Oh by the way I am having extremely heavy periods problem due to fibroids since January....sometimes do feel a bit bloated and am currently on a progesterone pill to stop the bleeding before they take out the fibroid. Can gynae issues cause such weight gains?
My food intake is more or less same. I used to do 30 mins 5days a week brisk walk which is still continuing but not as regular as before (due to this heavy bleeding problem)

[swooosh]

I think 10lbs is a dress size.