Can I have a larger silicone implant when my saline expander implant is removed? (photos)

Hello Nevilv, 
Thank you for your question and for sharing your experience. It is possible for an implant slightly larger than your filled tissue expander to be placed at the time of your exchange procedure. However, this is a discussion you should have with your plastic surgeon, as you need an expert to assess the quality of your skin and determine the appropriate implant size for you, in person. 
As for the other breast, you will continue to have asymmetry after your exchange procedure. This is not necessarily due to the difference in the size of the breasts, though if you upsize your reconstructed size you will certainly have a degree of size imbalance - the asymmetry from your photo is also caused by ptosis, or natural descent, of the breast tissue on your left side. While placing an implant can help elevate the breast mound and nipple to some extent, the definitive treatment for this is generally a breast lift (mastopexy), though you need an in-person evaluation to determine the correct way forward.