That bottle should last you 18 months or more...I can't answer for sure because I haven't done full-head applications for so long. My 33 oz bottle of Gold lasted for nearly 3 years, with me doing primarily root applications every 5-8 weeks. I have dense, waist-length hair, but it's baby fine, so it doesn't appear
to be as thick as yours. You shouldn't need to keep re-doing your hair over and over after a point...you should be able to get by with root applications. I did 4 back-to-back full-head applications in the beginning to get my curl pattern where I wanted it.
I think Kerapremium would be your best bet. Organiq Gold did almost nothing for my hair except make it soft, which is an unwanted side effect of BKT for fine hair. I was disappointed, and I was stuck with a 33 oz bottle until I was able to sell it.
If you'd be interested in splitting the bottle of Kerapremium, let me know.