Well, it's good that you have a positive relationship with your parents; loyalty to one's family is a great virtue. And frankly, your relationships with your relatives are likely to last a lot longer than with most friends/acquaintances (for better or worse) simply because the ties that bind a family together are established from the beginning and are generally maintained. Many friends/acquaintances will cross paths for a time but quietly break away later on, and have little if anything to do with your life (or you with theirs) simply because life takes people in different directions.

That being said, having positive relationships with those outside your family is important as well. It's interesting that you said that your parents encourage you to spend time with your friends; out of curiosity, do they simply tell you to do so, or do their actions suggest this as well? I only ask because I feel like, in my own case, my parents gave me similar advice, and I didn't doubt the basic sincerity of their intentions, but that many of their actions had quite the opposite effect.

In any relationship, parent-child included, one person can jealously vie for the company, affection, trust, free time, etc., of another, without necessarily ever realizing it. I'm not saying that this is the case in your relationship with your parents, but it's just something to keep in mind and look out for. Positive self-esteem does rely partly on having the sense of a strong individual identity, and if one ends up feeling like they are dominated & defined by others (family, friends, romantic partner(s), etc.) then it just breeds bitterness & resentment.