How can i play without having enough ram?

[PiggyMC]

It should be possible (atleast i hope it is) because the old launcher allowed you to do it 

i can use 1.5 GB but i need 2

[Munaus]

If you have a 64-bit OS then you can download the 64-bit Java that allows more RAM to the game.

Google java 8 64-bit, and make sure you close the launcher completely after installing it, it should detect and automatically use the new one. If not, when you're on the launcher and the Modpack screen click the Launcher Options and the Java tab. This will show you which java you have installed and how much memory you can allocate.

Do not use Java 9 or 10, they do not work with Forge.

Don't allocate more RAM than what your pc has. If you only have 2gb RAM then giving 2 to minecraft will suffocate your pc. Your pc needs 1gb RAM to work in the background