V05 with collagen (I'm assuming V05 Kiwi Lime, that's the one I use) IS a conditioner with protein. Hydrolized collagen is a pretty strong protein. If other conditioners make your hair too soft and limp they are OC'ing you and that causes frizz as well. Do you low-poo at all? Try low-pooing once a week if you think you have conditioner buildup, I like Yes to Carrots and Giovanni TTTT. And definitely try a protein treatment, what you described as soft and limp means you need more protein. IAGirl has a great homemade, cheap, and easy gelatin PT recipe posted in the 2's section. Gelatin is collagen as well, the same kind of protein in the V05.

I also use ION Effective Care from Sally's as a daily RO conditioner. It's pretty protein packed but it's also pretty moisturizing, I low-poo almost every time I wash my hair so I need it but you may or may not need that much moisture. If you up your protein usage though, you'll want the added moisture. Some here use ION Effective Care as a PT by itself. My hair craves protein so much I can use it daily as a RO conditioner.

fine, thin, normal/(low?) porosity. Mod-CG. Usually I can't co-wash more than 1x a week, & sometimes I have to use T-Gel in rotation due to scalp issues.

Co-wash: VO5 Volumizing
Poo: Giovanni 50:50
RO:TN, Nexxus Youth Renewal, Alba Coconut
PT: gelatin PT, ION EC
Stylers: Giovanni mousse, TIGI Curls Rock amplifier (a-cone), Curls Rock Strong Hold Mousse
Gels: SCC spray gel