I started learning English since when I was 14 years old; now I'm almost 18.
I have been learning English since I was 14 years old.
You need to use the present perfect/present perfecr continous with the word "since".
4 years and still learning.
Languages are amazing. Full of different words, and vowels. I started learning English when I was 14 years old; now I'm almost 18. Many things have happened since. I entered to an English course and it was the best experience I have had. I met wonderful people and amazing teachers. At first, I started learning English informally. I didn't know anything about grammar nor subject-verb agreement which I now think are very important. The first year I was learning I didn't know ANYTHING about past participle. Well, I know now :) Thanks for having read my post.
<em>Very good!</em>