How do you know if a guy is really into you?

I'm 15 just to start off. There's this guy in my bus and we both have been really flirting and we've been texting for the past two weeks and we've already kissed once. But I feel like he already got bored with me because he walked me to class today like he always does and he didn't put an arm around my waist like he usually does it or try to like sneakily hold my hand. We had made plans to go out this weekend on Valentine's Day but I'm afraid he's going to blow me off like last weekend when we were supposed to hang out. Should I asks him about it or am I completely just blowing this out of proportion??