I could have stopped there but I hated to let something so simple end in failure. I decided to give it a second try. Luckily I found the correct rice (I live 30 minutes from a medium size store and an hour from a large one) and set out to correct my mistakes.
The second try turned out great! I'm so glad that I decided to give it another chance. On the second try, the pudding thickened after about 45 minutes. It had a perfect creamy consistency and wasn't too sweet. It tasted great warm or chilled. I didn't add the chocolate this time but might in the future.
Thanks to OSI: Isabelle from Les gourmandises d’Isa for choosing this recipe. I will definitely be making this again!