4.4 = i370 to i400?
This ilvl progression loops every tier. So, for 4.4 the crafted gear will be higher than the current top ilvl.
i380 (crafted + omega 9-12 normal) > i390 (New tomestone gear) > i400 (Augmented tomestone/savage gear). There will also be new extremes to farm items too, which should mean upgrades too depending on your equipment.
Getting Good
There is only one way to get really good, and that is through experience! For example, lots of the savage fights have mechanics that have already been used in many previous fights. Sigma 5 Savage has mechanics from sigma 5 normal and a chain that is similar to Ifrit Extreme. Shinryu Extreme has mechanics from nearly all the previous extreme fights.
Checking your DPS: Sky Stone & Sea
There are testing dummies for every Extreme and Savage fight since Heavensward. These dummies are tailored for each class and to see if you have the power to take down the boss. Generally, if you can clear the dummy for a challenge then your DPS is good enough to win the fight (as long as u don’t die & play well). You can even put in your results on this website http://ffxiv.2digitalgames.de/ If you are struggling to beat the dummy and you have the right ilvl it may be worth looking into improving your rotations/opener, and tweaking your stats to maximise damage potential.