Is it normal to suddenly look 3 m pregnant, 2 m after Tummy Tuck when your stomach has been perfectly flat all along?

Some swelling an inflammation is normal after any surgery. Unfortunately, no worthwhile advice can be given from reading your description and looking at your photos. Discuss your concerns with your surgeon and if you are not satisfied with their explanations consider a second opinion.

It is hard to tell what might be going on based on these photos alone. An examination would be very important in making an appropriate assesment. For the best results seek the consultation of a
plastic surgeon certified by the American Board of Plastic Surgery. They have a
website listing all the certified plastic surgeons. Members of the American
Society of Aesthetic Plastic Surgery will all be board certified in plastic
surgery and have demonstrated an interest and competence in cosmetic plastic
surgery as well

wish i could say what is going on from your pix and history, but i can't. you should be closely followed by your surgeon and these concerns should be discussed. if you haven't been seen recently, you should schedule an appointment for a recheck soon. if you are not comfortable with what you are hearing, it is never a bad idea to think about getting a second opinion.

I'm sorry I can't help more, but it is very difficult to tell what is going on via your description and pictures.  You can always seek a second opinion of a board certified plastic surgeon in your area.Good luck.  Healing takes time.