i put silicone implants 690 cc completely under the muscle 2 years ago..

At two years post-op breast augmentation surgery, it is unlikely that your results will change further. Consult with a board certified plastic surgeon to discuss revisionary surgery if you are wishing to change the look.  Remember that revisionary surgery is tricky and no result is perfect.  
Clear communication with your plastic surgeon is important in achieving the desired goals of the patient.  I like to communicate with patients with “goal” pictures.  During surgery, I use temporary sizers to determine the size/profile that will give the patient the look she is looking for.  When I have the patient in the operating room, i adjust the size and pocket to try to get the patient's desired look.  Not all surgeon's perform revisionary breast surgery so do your research and find one that you connect with and like the results you see.

After two years, it appears that you may have developed caspular contracture if your breasts are firmer now.  They will most likely not soften up on their own.  You probably need to undergo a breast revision by an experienced breast revision plastic surgeon.  You may need to remove the scar tissue, change implants to something wider, lift the breasts, etc.  Revision breast augementation is not an easy thing, so investigate your surgeon and make sure he/she does alot of revisions.  I hope this helps.

Your breast implants have settled into this position and will not change any further since your surgery was done two years ago. Based on the photos I would not recommend any additional surgery to attempt to create cleavage either. A board certified plastic surgeon can evaluate you in person and give you more specific answers to your questions.

Best wishes,

Dr.Bruno