I have a huge swelling/seroma on the right side but it doesn't hurt? (Photo)

Dear Tsuyakeshi, Thank you for your question and congratulations on your operation. It does appear that you have a fluid collection which needs to be drained. I suggest scheduling an appointment with your Board Certified Operating Surgeon to address this sooner than later. This should not negatively impact your healing, so long as it is treated timely and properly. Best of luck to you! 

It could either be a seroma or a hematoma.   Hopefully, it is a seroma as addressing this is easier.  If it is a seroma, I would recommend aspiration of the seroma followed by compression (may require multiple aspirations).  You don't want to wait too long before addressing this as a chronic seroma can create a capsule and will not allow the chest skin to stick down to the underlying pectoralis major muscle.  

. . . which is a generally benign fluid collection, and should respond to percutaneous needle drainage (if firmer, however, could be hematoma, which would take longer to liquefy and resolve - also may threaten overlying skin, and possibly nipple perfusion). Otherwise, the only real risk is an infection developing (and possibly - if long-standing - stretched skin compromising your result), so needs to be monitored, and at least covered with po antibiotics for the time being (with good compression), if no one is willing to intervene - but drainage of some sort would be the more definitive approach (I'm assuming you're not still in the same town as your surgeon, otherwise should be easily addressed . . . )

The swelling appears to be either a seroma (clear or yellowish fluid) or hematoma (collection of blood clot/liquid blood). If it is getting smaller in size, continue to observe, but if it's stable, you may want to consider drainage either in the clinic, or a radiologist can do it under ultrasound guidance (which is not always needed. The only risk with leaving this for too long is that the body can form a capsule around the fluid collection, which will prevent all the tissues from healing together properly. If it is not greatly improved in the next week, I would advise pursuing drainage.