...and AFAIK he doesn't use swap partitions either.
Quite so, Alex -- 77 Linux Distros on this Dell rig and not a skerrick of swap amongst them, other than some zswap coded in by some Developers. Only reason you need a swap partition is if you Hibernate (which I don't).
Since the partition for your install is not allocated with enough space a fresh installation is the best choice.
That is certainly an option.
Welcome to linux.org
@matanspada .
I note from the pictures you have provided that you have maybe about 28 GB of space consumed between your root partition p6, and your home partition p7, on the SSD. With 12 GB of that being in /home , you may be a Gamer or otherwise use some very large files for some other activity?
So you may not be in a hurry to reinstall.
I have to leave for my evening DownUnder shortly, I will be back tomorrow with more detail if you need it.
I would provide 2 options - one involves using Windows Disk Management tool to reclaim maybe 100 GB that can then be used for Linux, and then use GParted from a LiveUSB (install) stick to reshuffle the rest in position and size.
The second would involve doing a reinstall, and in the Ubuntu Installer (known as Ubiquity) choose "Something Other" or "Something Else" to do some hands on manual partition choices. With that, you might want to safeguard your data elsewhere first.
With Windows I would be first running a Defrag, and put in place a Recovery Plan (eg Rescue Disk), and that applies with either option.
Cheers for now
Chris Turner
wizardfromoz