I'm a beginner too, and completely understand your frustration about getting your fingers to do what your mind is trying to tell them! :-)
Here's my philosophy about the learning and adapting process:
1) We each learn at different speeds and in different ways - the process will take as long as it takes for you, but each additional minute you practice will improve your guitar abilities, imperceptible as those gains may be at any moment in time/in the short term
2) Frustration in "nailing" a chord shape or a set of notes to make up a tune is to be expected. The more often you attempt to repeat the chord shape or pattern of notes, the better your brain adapts to the pattern, and the better the muscles and tendons adapt to the pattern - much of this is what is called "muscle memory"
3) We learned to walk and speak at least one language through constant practice and repetition - we forget how long it took to become proficient in both of those activities, but we know it took a matter of years
All I can say is "keep the faith" that you will get better, expect to feel that you will have off days where you feel that you are taking two steps back, and dedicated practice and repetition are one of the key contributors to progress.
I'd be very much interested in hearing other peoples' philosophy on how to overcome frustrations about speed/lack of progress in learning various aspects of the guitar playing process (i.e. what mental techniques should we apply to ensure we keep a positive approach to practicing and progressing our guitar skills?)...
Carpe Guitarplay Diem