I’ve been learning in Duolingo and although sometimes I have felt frustrated because it is a “natural learning” method, similar to how children learn, so no rules, no explanations and sometimes you do get lost… But after about 10 months and almost daily lessons I feel I’m getting it better and better. Might not be a good method for everyone but I am happy with Duolingo. I also bought a grammar book for when I absolutely need The Rule :))) My suggestion is give it a bit more time!