Why would my breasts be larger after extended tummy tuck with MR and lipo?

Congratulations on your surgery. Liposuction in the area can cause fluid to accumulate. I'd recommend discussing your concerns with your surgeon, but I would expect that the swelling will improve completely over the course of 3-6 months. 

Stressful situations such as surgery can cause hormonal changes that affect the breasts. This is usually just sensitivity or tenderness but can also lead to temporary lumpiness or increases in volume. Having said this, the most likely cause of the increase breast size is the liposuction. Liposuction is very traumatic to the tissues and will invariably cause swelling. As you are obviously concerned at this time, it would be appropriate to visit your surgeon for a thorough explanation and assurance.

Thank you for your question. After surgery, there can be significant shifts in fluid volume and swelling. This is likely what has caused the change in your breasts. I would advise you to discuss this with your surgeon but I would suggest that this will resolve back to normal with time but may take 3 months or more, so be patient.Hope this helps!

is the most likely explanation for your perceived increase in breast size.  Unless your weight is increasing as well, your breasts will return to its pre-op size as you continue to heal.  You can get more reassurances from your surgeon in your follow-ups as you should address this with him/her.