His parents are insisting that he makes his clothes long (isbaal)

Firstly: 

Isbaal means letting the clothes hang down below the ankles, which is haram, because the Prophet (peace and blessings of Allah be upon him) said: “Whatever of the izaar (lower garment) hangs down below the ankles is in the Fire.” (Narrated by al-Bukhaari, 5787)

If someone were to say, “I do not let my garment (or pants) hang down below the ankle out of pride, but because of habit or custom,”

Our response is:

That isbaal (letting the clothes hang down below the ankle) in and of itself is subject to the punishment of Fire. If pride and showing off are added to that isbaal, then the punishment is worse and more severe. The Prophet (peace and blessings of Allah be upon him) said: “Isbaal may apply to the lower garment, shirt or turban. Whoever lets any part of them hang down in order to show off, Allah will not look at him on the Day of Resurrection.” (Narrated by Abu Dawood, 4085, and al-Nasaa’i, 5334, with a saheeh isnaad).

Secondly:

If you know the ruling on isbaal and that it is haram, then you and every Muslim must keep away from haram things, especially major sins. It is not permissible to do something haram in order to please people, not even one of your parents, because the Prophet (peace and blessings of Allah be upon him) said: “There is no obedience in disobeying Allah; obedience is only with regard to what is right and proper.” (Narrated by al-Nasaa’i and Abu Dawood, and classed as saheeh by al-Albaani in Saheeh Sunan al-Nasaa’i, no. 3921; al-Silsilah al-Saheehah, 181). Remember what the Prophet (peace and blessings of Allah be upon him) said: “Whoever seeks to please Allah by angering people, Allah will suffice to protect him from people, but whoever seeks to please people by angering Allah, Allah will abandon him to the people.” (Narrated by al-Tirmidhi in Kitaab al-Zuhd, no. 2338).

With regard to your fear that you may lose your job, know that provision is in the hand of Allah and no soul will die until it has received all its allotted provision. 

Remember the words of Allah (interpretation of the meaning): 

“And whosoever fears Allah and keeps his duty to Him, He will make a way for him to get out (from every difficulty).

And He will provide him from (sources) he never could imagine. And whosoever puts his trust in Allah, then He will suffice him. Verily, Allah will accomplish his purpose. Indeed Allah has set a measure for all things”

[al-Talaaq 65:2-3]

This fear does not allow you to commit a sin. 

If someone were to ask, if I am forced to do something that is haram, am I allowed to do it?

The answer is:

You have to make sure that one really is being forced. If the matter reaches the level of compulsion, and a person is compelled to do something, then it is permitted for him to do whatever he is forced to do out of necessity.

For example, if a father tells his son that if he makes his clothes come above the ankle, he will kick him out of the house, and the son cannot find anywhere else to live, and he is certain or thinks it most likely that his father will carry out his threat, then he is permitted to make his clothes longer until Allah gives him a way out. 

Thirdly: 

With regard to your saying, “I do stick to this sunnah”, you should note that making the clothes above the ankle is obligatory, it is not only Sunnah. The Sunnah is to make the izaar (lower garment) come to mid-calf, and this Sunnah is optional. If a person wishes, he may do it, and if he wishes, he may not do it. Sunnah, according to the definition of the scholars, is “That for which the one who does it will be rewarded and the one who does not do it will not be punished.” 

Note that what is to be worn at mid-calf length is the izaar (lower garment). The thobe (galabiyah) is not to be worn in this manner; rather the Sunnah in the case of the thobe is to wear it below mid-calf and above the ankles. The same applies to pants, which should be worn above the ankle because the Prophet (peace and blessings of Allah be upon him) said: “The ankles have no right to the izaar.” (Narrated by al-Nasaa’i in Kitaab al-Zeenah, no. 3529; classed as saheeh by al-Albaani in Saheeh Sunan al-Nasaa’i, no. 4922) 

And Allah knows best.