Conversion to Islam

Bismihi ta'ala

The fiqhi ruling for this is the same for any wali amr, and she would need the consent of her father, whether he is Muslim or not. This is in the case that she has not been married before and is not completely independent in everything she does (balighah/rashidah). 

And Allah knows best. 

Bismihi ta'ala

Numerous reverts I have interacted with did face similar issues, where they feared backlash, and had to conceal their Islam. They would pray in secret, and so on. 

In answering your question, in your circumstances, your prayer will indeed be valid.

What I would like to recommend is that you correspond with other fellow reverts from your same background, and find feasable ways in how you are able to overcome some of the struggles and difficulties you might be facing. 

May the Almighty give you strength, and bless you for your accomplishments.  

Bismihi ta'ala

Our Islamic method of praying can only be recited in the Arabic language, making sure pronunciation is as best as possible. 

If you are new to Islam, it is important to take gradual steps in familiarising yourself with the religion as much as possible, especially the doctrinal and moral aspects of the religion. As far as salah is concern, you must recite it in Arabic. You are able to read from a book, or follow a pra-along tutorial, or ask someone to assist you, until you memorise the blessed surahs and dhirks of prayer.

Of course, at the same time try to get to know the inner dimensions of prayer and also what the translation of what you are saying.  

With prayers for your success.

Bismihi ta'ala

There must have been many things you had to deal with when you first converted to Islam. This is very common, and you should take things on a normal pace so you familiarise yourself with the precepts of this new religion you have adopted. 

As for praying, there could have been alternative options, where you could have avoided upsetting your parents, and also observe your daily prayers. Like, praying in closed off area, or bedroom, etc. 

What you can do in your free time and gradually pray these days, as qadha`, or as re-doing that which was obligatory for you which you missed out on. See it as a blessing, as when we pray, although more than our daily routine, that is indeed an honourable blessing from the Almighty, as there is nothing better than worshipping Him. 

With prayers for your success. 

Bismihi ta'ala

It's greatly noble that they are very good people, and for sure their nurturing contributed to your personality as well. 

As you know, religion and becoming religious is a choice that must come from within. Even as Muslims, we always pray to Almighty God to keep us "guided" on the right path. Hidayah, or guidance is in the hands of the Almighty.  If your grandparents, or anyone else around you has a potential that Allah ta'ala sees in them, then they will be guided to the light of Iman. If they do not "convert" to Islam, it does not mean they are evil, but just that hidayah is with the Almighty. 

The best thing you can do is set yourself with high standards in your conduct, in your ambitions in life, and show those around you how a true Muslim should be. 

That itself is a great form of conveying the message of Islam, and then it is up to them to investigate, or ask questions, and so on. 

If you see that your grandparents are interested, or have questions, discuss what you know with them. However, never allow it to become an argument, or upset them, as they are your grandparents. 

In any case, always do dua for yourself, your parents, your grandparents, your siblings and everyone else, that God showers them with His compassion and Mercy. Ask the Almighty to enlighten your hearts, and ask Him for guidance. 

You can also do tawassul to Ahlul Bayt (a.s.), to give you the strength you need, and introduce them to Ahlul Bayt (a.s.), in a positive manner. You dont know what the outcome will be, but at least they will think positive of your religion, and understand you more. 

With prayers for your success.