Welcome to PC.
First of all, none of your questions are stupid. In fact, you are quite smart to raise these questions in the first place since most people spend their whole lives without facing these questions.
I will attempt to answer your questions but my responses would be mere perspectives. I don't think there are definite answers, but at least you will have different perspectives to ponder upon and figure these out yourself.
1. The answer lies in your actions and choices. If you do things (or at least try these) that makes you comfortable, brings you joy and earns you peace; then you love yourself. In my opinion, this is something natural and programmed in us to love ourselves. This love for ourselves dictates our choices (both good and bad) and we do the things which make us happy (at most) and survive (at least).
2. To me love is the spirit of life and thus shows in all our actions. The air you breath, the sunlight you receive, the water you drink - it is the love of nature for you; the things your parents and family do for you - it is their love for you; I think you feel loved when you receive without an obligation to return. And yes we love others (sometimes less and sometimes more - but we do love)!
3. I think here you should not focus on the words and rather see the intent behind these words. She wants you to be happy and sociable. Now people face different challenges when it comes to social interactions. For some people, it is quite a straight forward phenomenon and comes very naturally to them. Then there are others for whom such interactions are a challenge... With experiences (both good and bad) that you have had during your interactions, you should start using these and build your relations using your experiences. For example, I will not invest myself emotionally into a classmate who does not respect me (or others) and has nothing to offer in return. On the other hand, people who are nice and caring, I will devote my time and attention to them. Occasionally, there would be cases where people with apparently good intentions will harm you; that's where you experience from bad experiences will come in handy and with some skepticism and forethought, you'll manage.
In a summary, life is not easy and there is no formula or recipe for it. We all have to figure it out ourselves in the end. So try to hang in there, take small steps forward, be ready for set backs and be prepared for not giving up.
Good luck!