Your thesis is not very clear.
- it needs to be a full sentence that is taking a position or making an argument.
- try using "should" is the easiest way, e.g. "all Thai students should be required to learn a foreign language in addition to English"
Your body 3 counter arguments are very good but you need to also "disprove" or "discredit" these arguments and show that your side of the argument is more convincing.
- e.g. .....even though there are these difficulties and negative sides to learning a foreign language but the advantages still outweigh the negatives.