American here. Ask me anything.

名無しさん＠英語勉強中

>>66
In this sentence "English" isn't owned by anyone; it's simply the concept of the English language.
If I had to pick between the two you've listed I would say the second one is the closes to the intended meaning.

>Feel free to ask me for help with my English.
This means that the speaker is stating that questions regarding his or her own English are encouraged.
The speakers English is stuff like sentence structure, word use, verb tenses, etc. that specifically the speaker uses (as opposed to anyone else's usage).

>Feel free to ask me for help with your English.
This means that the speaker is stating that questions regarding the listeners English are encouraged.
Since the speaker can't know all of the English that the listener uses, the questions could be about anyone's English.

>Feel free to ask me for help with English.
This means that the speaker is stating that questions regarding English are encouraged.
Since the questions are about English in general, it could be English etymology, phonetics, syntax, pronunciation, topics covered in classes called "English," style, usage, etc.
Although in this context, the intended meaning is probably limited to colloquial and/or formal usage as a layman probably only has a small understanding of the other topics.