I also use protein only in a RO and I still follow with a protein free conditioner. Type of protein, for me, doesn't seem to matter but it does for some as the op mentioned. I laid off protein completely for a short time but discovered my hair needs some - most do need some. It's a matter of finding the type and or amount for your hair. But you have been using protein when you thought you weren't so be extra discerning with your ingredients as you figure this out. You can also do a stretch test every time you wet your hair to see if you should use a protein RO or regular. You'll get there!
remember, with all advice or suggestions for your hair, YMMV!!
My hair:
2b wavy, medium texture, low porosity, med-high density. Protein finicky.
My routine:
Cleansing: DCNP, every 4-5 days (occasionally use CJ cleansers).
RO: CJSC, occasionally use JCDC
LI: KCKT or CJSL
Gel: KCCC, CJCIAB for 2nd day hair (sometimes third)

Heat is my friend: warm water rinses, steam caps, and diffuse dry. I love CLU cloths and my Denman.