I do something similar. I backup my apps using Titanium Backup, and I to ONLY back up apps not system data ive done both ways and when I backed up the SYS Data I would sometimes get force close issues etc. I also use SMS backup/restore and backup my text messages (make sure u are backing up all this stuff to the external SD card not internal SD), I also use a file manager to make sure I got everything off internal memory an move it to external SD. Then I boot into Recovery Mode, wipe data, wipe dalvik, cache etc, ill flash my new ROM and then wipe dalvik and cache again (maybe pointless but I always have succes so Im not changing my ways now lol) after all that then I reboot and wait for it all to settle in, then sign into everything etc, and then for good measure, after its all done I power off and take batt out for 30 sec and then put it back in and power on and im good!
Been doing it this same way for years now and this is what works for me.
If u need help just let me know.
Sent from my Sexy Samsung S5