3-month old laptop with Windows 8, I'd be VERY surprised if it wasn't 64-bit.
If you go onto My Computer (Probably is named This PC in Windows 8.1), right click, and click properties, you'll see the OS details. You'll probably see "64-bit Operating System", which is a good thing. If you see 32-bit, then you'll have to upgrade.
Your Windows license supports both 32 and 64 bit versions, so it's a matter of getting your hands on the DVD. Again, I doubt you'd have a 32-bit version of Windows 8.
Next proceed to uninstall ANY version of Java you have running, download 64-bit Java from Oracle's website (Google it - the download for 64-bit isn't very obvious) and install it.
Then load your FTB Launcher, click the Options button on the top (has a gears icon next to it) and you should see a slider. If 64-bit has been installed properly, the slider should go further than 1GB.
On my 4GB machine, I find 2.5GB to be the sweet spot for running Monster, so if you're aiming for Direwolf20, 2.5GB will be more than enough.
Hope this helps.