Is there a way to fix my uniboob? (photos)

I don't understand the rationale for going with larger implants to fix symmastia, since they will be wider and put more pressure on the skin between the breasts. To correct the problem you will probably need narrower implants.

I am sorry to hear about your concerns after breast surgery.  
 
In my practice, having used a variety of “techniques” for correction of symmastia, I find that the most reliable technique involves a 2 layer capsulorrhaphy (internal suture repair of the breast implant pockets along the cleavage area). Often, the use of acellular dermal matrix is helpful also. I have also been pleased with the (at least partial) correction of skin tenting that can be achieved with the use of the acellular dermal matrix.
 I also find that careful attention to postoperative activity restrictions is key to success with this type of surgery and other types of implant malposition revisionary breast surgery.  Activity restrictions are individualized patient by patient, depending on exactly what was found and done during the procedure.  For example, for most of my symmastia  patients, I ask that they avoid pec major related exercises ( especially exercises that involve abduction of their arms) for at least three months after the procedure is performed.
My best advice: select your plastic surgeon carefully. Make sure that he/she has significant experience achieving the types of outcomes you will be pleased with. Then, communicate your goals carefully. Working together you will come up with a good plan to achieve your goals.   
 Best wishes for an outcome that you will be very pleased with.  

Yes, this can be fixed, but you will probably need to go with smaller implants to decrease the chance of a recurrence. This can happen when the implant is too big/wide for your chest wall.