This snipped from the Technic Discord will fix you:
You're running a 32bit Java version on a 64bit Operating System. This will prevent you from allocating more than 1GB of ram to the Technic launcher. In order to update to Java 8 64-Bit, please follow these instructions: 1.) Close the Technic launcher. It should not be running! 2.) Open http://java.com/en/download/manual.jsp in your web browser 3.) Download the version that has 64-bit in it for you operating system. If you're using Windows download the one that says Windows Offline (64-Bit). 4.) After the download is complete. You must install it. You can do so by double clicking on the icon to run it. 5.) After it installs start up the Technic launcher again. 6.) Click on Launcher Options in the top right of the screen. 7.) Click on the tab called Java Settings 8.) Click on the dropdown called Minecraft Java Version and select the option that says 1.8_151 64-Bit. 9.) Click the dropdown called Memory and select an option that's between 2 GB and 4 GB. Do not select an option higher than 4 GB!