Granted, they haven't been touched in 6+ years, but Mids Hero Planner is still viable and useful for everything but Sentinels. Start messing with builds, there.
Longer version, at low levels, you're going to be sucking wind, A LOT. Abuse the Rest power to recover in-between mobs, use inspirations to recharge, and/or just wait. Your attacks are definitely using more end/sec than your toggles are. Add Brawl into your rotation as a Brute, it builds Fury, recharges fast, and has little/no end cost IIRC. Then, use your bigger attacks to finish off the mob. Slotting is a mess at low levels, as you get higher up, you'll earn more slots for your powers, and also gain access from Training Origin to Dual Origin to Single Origin (each is 2x as strong as previous). There are also Invention Origin enhancements, which the generic ones are as strong as SO's, and the Set IO's can be a weird mish-mash.
Also, with Energy Defense, your Defense shields are typed off of the damage - Fire, Smashing, Lethal, et alia... Look at what the mobs are trying to hit you with, and try to run the ones best suited. Always run your mez shield, though. While I didn't do Kin, I did do a DM/Nrg brute to 50 back in the day.... once you get up in levels, it is hilarious fun... sneaky/smashy/punchy fun.