The 24-year old Republic of Ireland international is currently on loan from Preston North End and is loving his time at the Riverside so far despite a horror start.
"It has been a difficult few weeks," St Ledger told the club's official website.
"Coming in and losing 5-0 (to West Brom) on your debut is tough and I was desperate for my first clean sheet and first three points.
"I think there is improvement all round and I'm really pleased to have made the move.
"I'm settling well, I enjoy playing in the side, it's a young side and we're getting better. It'll take a few games before we all settle to show our best, but so far there's a lot of promise.
"It's been a strange few months for me really, but I've settled in very, very well with the manager (Gareth Southgate), he is a good guy, a top bloke and I'm enjoying it."