Bismillahir Rahmaanir Raheem
Al Jawaab Billahit-Tawfeeq

Respected Sister,

From what you have mentioned, it is clear that you have intentions of marrying this particular brother. Alhamdulillah, by means of tying the knot, insha Allah you will be saved from the many fitnah and fasaad (trials and corruption) which many youth face nowadays because of their unwillingness to get married.

In Islam, there are certain ways of doing things so then one's actions will always comply to Shari'ah. Similarly with marriage. Unlike the non Muslims who promote relationships prior to marriage, Muslims should not succumb to that level.

We try to the best of our capabilities to avoid any form of contact with na mahram. What this means is that, we express our desire to get married to a particular individual via our mahrams and female relatives only.

In your case, the best would be to convey your desires via people like your father, brother, uncle etc. Tell them about the brother you wish to marry and then get your mahram relatives to do some investigations of the brother (eg. Is he interested? Does he want to get married too? Is he actively seeking for a spouse? etc.).

Later on, if the brother expresses his wish to wed you too, then you together with your family members and his family members should take further actions to proceed with the preparations. Always bear in mind to observe Shari'ah laws and restrictions throughout the procedure.

Finally, it is highly urged to make solaatul istikhaarah to seek guidance from Allah. Act according to the result of the istikhaarah. If it is not in your favour, then you should muster courage to stop everything. Have faith that Allah has better plans for you insha Allah. Otherwise, there is absolutely no harm in carrying on with the marriage.

Also, one should avoid from thinking about any na mahram as to do so will be sinful. Make taubah and ask Allah for sincere forgiveness if at all any thoughts of the brother came to mind. Then, make a firm intention to never again think about the brother or any na mahram for that matter in future.

And Allah knows best.

Wassalam.