Are nipple sensitivity and erection controlled by the same nerves ?

No they are not.  There is overlap and dual innervation.  Many stimuli can cause erection.  However, I would still take it as an encouraging sign that you will eventually gain some sensation if not completely.

The sensory nerves to the nipple are very sensitive especially to stretching caused by the implant which I believe is the most common cause for numbness rather than being cut. Fortunately as the tissues soften, the sensation often returns with in the first year. If your nipples can become erect then in my experience you will have more of a chance to regain sensation.Nipple erogenous sensation recovery and the rest of the skin of the breast where you describe numbness are from different nerves. Although it is highly likely that you may not have return of sensation, the good news is the vast majority of patients will have return of sensation within the first year after breast augmentation.#breastaugmentation#numbness

It is different nerves, but the fact that your nipple gets erect is a really positive sign that you will eventually regain sensation. It can just take a long time for the nerves to regenerate. Best, Dr. Nazarian