I never had a fish finder and did pretty decent. I always fished points and current seams, fish typical areas fish concentrate.
From the sounds of it you are doing far better than most guys, especially just starting out. Don't get to greedy trying to improve what isn't broke. Be glad to have the success you're having and keep putting fish on the punch card.

I use to row my little 10ft Jon boat out and jig at Lincoln park and three tree point. Also out in Elliot bay. 3 to 5 fish a week was my normal success rate.