Khan promotions operator Amir Khan and Nevin had reportedly come to a deal to bring the Mullingar boxer into the professional ranks but that deal fell through and Nevin has now signed up for the semi-pro World Series of Boxing.
"It's been very difficult, I got a lot of big offers in and you couldn't blame me for viewing them and looking at them," he said.
"I decided I'd go professional. But I got a lot of time to think before signing the contract and decided to go back and give it one more go for Rio, and try and take home a gold medal.
"I said after the fight against Luke Campbell in the (Olympic) final, 'I slipped up'. I wanted to go into that membership of Katie Taylor and Michael Carruth of having gold medals. But hopefully I can take it (in Rio) and be in that list.
Swimming: Australian five-time Olympic champion Ian Thorpe has revealed that he battled depression and thoughts of suicide during his record-breaking career.
The 30-year-old has opened up about his troubles away from the pool that led him to consider taking his own life.
He also recounted that he had been too "embarrassed" to tell even his family about the disease until this year. "I realised that I had depression early. I was having treatment for depression when I was a teenager," he said. "Depression comes in bouts. You can feel okay most days and then just get hit with it. I experienced that through what was mostly a very successful swimming career."
Athletics: Indian authorities investigating a rape case say a sprinter who won a women's relay gold medal at the 2006 Asian Games is actually a man.
Police charged Pinki Pramanik on Monday with raping and assaulting a woman she was living with in the eastern state of West Bengal.
The woman alleged Pramanik was a man who had reneged on a promise to marry her.
Indian authorities say an eight-member medical board submitted a gender test along with the charge sheet that concluded Pramanik was genetically male.