All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
All praise is due to Allah, Who guided you to Islam and faith. It is really a great favor and enormous blessing for which you have to thank Allah Almighty by your heart, tongue and other body organs. Allah Almighty says (what means): {And [remember] when your Lord proclaimed: If you are grateful, I will surely increase you [in favor]; but if you deny, indeed, My punishment is severe.} [Quran 14: 7]
We would firstly advise you to start unveiling the fact of your conversion to Islam gently and gradually, as this could be better for you than to keep the matter hidden. This is likely to keep you away of much embarrassment and hardship in terms of observing religious duties and acting according to the Commands of Allah, the Exalted. In your endeavor to do this, you may experience a great deal of suffering and hardship, but with patience and certainty, you can overcome all these difficulties. You have a good example in the Prophet, sallallaahu ‘alayhi wa sallam, and the Companions . Addressing them in the Quran, Allah Almighty says (what means): {Or do you think that you will enter Paradise while such [trial] has not yet come to you as came to those who passed on before you? They were touched by poverty and hardship and were shaken until [even their] messenger and those who believed with him said, "When is the help of Allah?" Unquestionably, the help of Allah is near.} [Quran 2: 214]
You can seek the help of these Muslim groups in order to defend you utilizing the laws that advocate the freedom of beliefs in these countries.
If you have no other choice but to conceal your Islam, then you are blameless to do so.
On the other hand, marriage is one of the best means to help you observe your religiousness. However, your wali (matrimonial guardian) must be a male Muslim. It is impermissible that a non-Muslim person assumes the marriage contract procedures of a Muslim woman. If you do not have a Muslim wali, then the judge or his deputy can assume your marriage procedures. In such a case, your family's approval is not set as a condition by the Sharee'ah. However, you have to be wise and seek help from Allah Almighty.
Study is not regarded as a necessity that allows you to take off the Hijab. However, if you expect that not going out for study will jeopardize your Islam, as your family or others may tempt you, then you are permitted to go out as much as is needed to ward off harm. Likewise, you are allowed to uncover of your body as much as is needed to ward off harm. You are not required to cut your hair or trim it. Harm is usually measured as one mostly believes it to be.
Finally, we advise you to fear Allah, the Exalted, to the utmost of your capabilities, and He will provide you with a way out and with relief in return.
Allah knows best.