In a year or two you should be ready to intern.
A more likely timespan, if you want to produce good developers, is five years with four years of study and one year of internships (in 3 month chunks). This is the co-op model adopted by Waterloo and it produces excellent entry-level developers.
If you want to be a reasonable developer, you cannot get away without being expert at least one low-level language (C or C++), one high-level language (Python, Ruby, LISP, etc), some knowledge of OS fundamentals (threads, processes, filesystems), some knowledge of concurrency (threads, locks, message passing), understand how to design your own language and build a compiler or interpreter (Flex/Bison, lex/yacc, etc), and a good base in discrete math (at the minimum, ideally some knowledge of numerical analysis and probability would be very useful as well).
This is exactly what you'd learn in four years of full-time study at a good university.
Why do you expect to become a good developer in 6 months by yourself when extremely intelligent people need four years of being taught (and being taught by a good teacher will normally accelerate your learning by 10x) to reach the entry-level stage?
You are being too hard on yourself. A year is nothing. Give yourself a few more years if you really love it and can afford to do so.