I don't have a recommendation for a 3.0 atomizer (other than a rebuildable perhaps) but I would also suggest playing around a bit with your airflow, wattage, and juices. It could be your juice ratio of PG/VG is too harsh for you in that setup. You may be able to make the N2 work for you. Everyone "recommends" higher PG in MTL setups but I am PG sensitive so I use primarily VG and 10% distilled water (now) but even at close to max VG, I was able to make that setup work, although I did have more coil gunking until I started DIY and adding DW. You probably do have some room to play with your PG/VG ratio, and I might recommend more VG to help with the throat hit, etc.
You could go to a carto but as has been said, that can get expensive. If cartos work for you though and other options don't, well, it may still be worth it.
Best of luck,
Anna