In the log we can see how much RAM you have allocated to the game and how much memory your system has left.
This log indicates that you allocate more RAM then your system has free, however as you have allocated the minimum amount of RAM to the modpack to run it reducing that is not a problem.
Thus your options are
Now, if you have a reason to believe the logs are not telling the truth about your system memory and have a clear indication for that to be the case that is not "it used to work before I changed stuff" then feel free to point that out.
This log indicates that you allocate more RAM then your system has free, however as you have allocated the minimum amount of RAM to the modpack to run it reducing that is not a problem.
Thus your options are
- find out what programs/background-processes you have running that you don't need while playing minecraft and closing them.
- Find some other way to reduce RAM usage by the rest of your system (possibly switching to another OS that needs less RAM, for example linux)
- Add more RAM to your system
Now, if you have a reason to believe the logs are not telling the truth about your system memory and have a clear indication for that to be the case that is not "it used to work before I changed stuff" then feel free to point that out.