Oh man, that explains a lot. The ideal scenario would have been if you reached that 345 light before opening the powerful engrams. Anyways, from now on the key is to make sure you are the highest level possible before you open your powerful engrams. Open them one at a time. Open one, infuse into gear/weapons that already have mods. Rinse and repeat. Once you have finish opening the powerful engrams for that character, log into your next character and transfer your highest weapons to it. Repeat the same process. After you're done with the powerful engrams on all your characters, manage gear between your character to balance them out. Coming next reset, make sure you start doing your weekly milestones with your highest level character first, that way when you "do the process" on your second toon it will end up even higher than your previous highest character.