Allergic to Silicone. What Are My Options?

In order to be allergic to molecule the body has to generate an antibody. There's never been demonstrated an antibody to silicone. Patients are therefore not immune to it. Therefore it is never rejected.

I have never heard of anyone with a real allergy to silicone.  It is such a ubiquitous material that it is almost impossible not to come into contact with it in some form or another every day.  I don't know of any breast implants that do not have silicone in the shell of the implant at the very least.  My only alternative suggestion for you might be fat grafting to the breast, assuming that you have enough fat to transfer.

All of the available implants have a silicone shell.  Some are filled with silicone gel, others with saline, but all have silicone.

If you have enough donor fat, the breast enlargement can be done with fat grafting. It has advantages and disadvantages compared with implants, but it is a good alternative for women who can't have or don't want implants. 

All the best.