2011-12: Forsling played for Linkoping’s U18 and U16 teams and played in three international games with Sweden’s U16 team; representing Ostergotland for the second time in the TV-Pucken tournament. He scored 5 goals with 3 assists and was +9 with 10 penalty minutes in 27 U18 regular season games and was +1 with 1 assist in three playoff games. Forsling scored 1 goal with 12 assists and was +5 with 4 penalty minutes in 16 games with the Linkoping U16 squad. He was +3 with no points nor penalties skating for the Sweden U16 team. Forsling was +3 with 3 assists and 6 penalty minutes in eight TV-Pucken games.
2012-13: Forsling appeared in 15 games, including one playoff game, for Linkoping in the U20 SuperElit league and was an assistant captain for the club’s U18 team. He played for Sweden’s gold medal-winning U17 squad at the 2013 World Hockey Challenge in Canada. Forsling had 1 assist and was +4 with 8 penalty minutes in SuperElit play. Forsling scored 7 goals with 8 assists and was +32 with 20 penalty minutes in 31 regular season games and was -2 with no points or penalty minutes in two playoff games for the Linkoping U18 team. In six games at the WHC he had 2 assists with 2 penalty minutes.
2013-14: Forsling played 44 regular season games and two playoff contests for Linkoping in his first full SuperElit league season and played for Sweden’s U18 team in the 2013 Ivan Hlinka Memorial and 2014 World Junior Championship tournaments. He scored 6 goals with 12 assists and was -3 with 36 penalty minutes during the SuperElite regular season and was -2 with 1 goal, 3 assists and 2 penalty minutes in the playoffs. Forsling played 10 games, including five playoff contests, for Linkoping’s silver medal-winning U18 squad. He scored 4 goals with 3 assists and was -2 with 2 penalty minutes. Forsling was -1 with no points and 6 penalty minutes at the Ivan Hlinka Tournament and led all defensemen at the WJC with 4 goals — finishing +2 with 1 assist and 2 penalty minutes — in seven games. Forsling was ranked 25th amongst European skaters in Central Scouting’s final rankings prior to the 2014 NHL Draft.