Minecraft locks at 450MB

Hello, I have an issue with minecraft: it keeps locking itself at 450mb RAM. I have tried all the normal methods to fix it, (Reinstall JAVA 64Bit changed the JMG arguments) Although I have set it at 3GB it does not use 3GB in game, in fact. it only uses 450-500MB. I have 16GB of RAM so that is not the issue. Inbefore someone links me to this post: https://www.reddit.com/r/Minecraft/comments/2n1drb/solution_minecraft_not_allocating_more_than_500mb/ I have already tried these methods and it did not help. I have reinstalled minecraft numerous times and nothing seems to work.

EDIT: I got it working. All credit to u/Parrelium If anyone else has this problem go to this link: https://www.reddit.com/r/Minecraft/comments/5j6gj3/how_to_allocate_more_ram_to_111/