None practicing in the family

I have 2 or 3 questions that i would like answered please, I am 21 years old, i have started practicing islam for nearly a month now, i have done a lot of sins in my life, taken drugs, drunk alcohol, had sex before marriage etc, i went to prison about 18 month ago and while i was in there i started practicing but when i came out i went went back to my old ways with the exception of drinking, about 3 weeks ago i started to practice again and repented for all my sins, i no longer take drugs or have sex, i am still with my girlfriend, she has converted as a result of the info i have given her about islam and her own research, my 1st question is how big is my sin of having a girlfriend even though i am not having sex? My second question is my family are not very religious my father recently told me he believes in allah and the quran but doesn't consider himself a muslim and my sisters don't practice, i have tried to give them dawa and advice but they say that they will do it when they are ready and also i have no right to question them when i have only recently started practicing and even though im practicing i have a girlfriend, what is the best way to deal with them, i pray for them every day after my salat, that allah gives them guidance and leads them in the straight path but what more can i do? I would very much appreciate it and be grateful if you could answer my questions. Allah Hafiz

In the Name of Allah, the Gracious, the Merciful.

Dear Brother,

I pray this message finds you closer to Allah Ta'ala and striving in His way.

Having returned to Islam in the context of prison, you will definitely encounter challenges as you adjust to practicing Islam in the outside world.
It is imperative that you surround yourself with a network of supportive, practicing Muslims who can help you along in your journey and catch you when you slip.
Unfortunately, this is not something that your family members can help you with. That is why you have to extend yourself to others by visiting the masjid, getting to know the imam, making good friends, and even traveling to seek knowledge and a better environment.
Alhamdulillah, you've resisted the temptation to succumb to alcohol and fornication. However, you have to buttress yourself further by breaking off your relationship with your girlfriend. As long as you are in a relationship, you will be tempted toward the unlawful. Clearly, committing fornication is the graver sin. However, Allah Ta'ala also commands us to close the doors leading to unlawful sexual activity. He says, "Nor come nigh to adultery: for it is a shameful (deed) and an evil, opening the road (to other evils)" (Isra', 17:32).
Emotionally, it will be difficult to leave the relationship. However, in the long run, it will be better for the both of you, especially considering that you both are trying to practice Islam. Perhaps, Allah Ta'ala will facilitate the two of you reuniting as husband and wife. When you do what is right, Allah Ta'ala places a lot of blessing, or baraka, in your life.
As far as your family is concerned, you're on the right track. You can't force them to want Islam. They have to want it for themselves and for the pleasure of seeking the nearness of their Lord. Continue to make dua for them and talk to them when you can.
For now, however, focus on seeking emotional and spiritual healing by turning to Allah Ta'ala in all your thoughts and actions, seeking His help and making repentance when you slip, and surrounding yourself with good Muslim friends.

And Allah knows best.