Relationship and possible pregnancy.

So, I’m having symptoms of pregnancy despite having protected sex. I’m 16 turning 17 on the 9th of this month. I subtly asked my boyfriend (who is 17) what he’d do if someone he was with was protected from a past relationship. He said he would leave, because if he were to be a father figure to any kids it’d be his own. Not gonna lie, that hurt me. Because we already started planning a future (yes I know, too young perhaps. But I can see us together in the future), and it would really suck if he left me because I ended up pregnant accidentally. I kinda laughed it off when he said that, and he laughed too, and we changed the subject. I’m getting a pregnancy test from my friend on Tuesday, and should find the results. I’m just scared that I will be alone if I am pregnant. My friend said her door was always open if I got kicked out, but surprisingly that’s the least of my worries. I’ve always wanted to be a mother, and if it was destined for me to have a child at this age, so be it. So I’m not scared of that either. It’s the fact that my boyfriend, whom says he loves me more than anything and anyone, would leave me if I was pregnant. That’s terrifying. Absolutely scary. I know I’d be able to get past it, but the fact that he already told me he wanted to marry me. Like... if you love someone, don’t you stick with them through thick and thin? I don’t know. My sister wants me to have an abortion, yet I don’t want to (again, IF I am pregnant.) I don’t know what to do. Any advice?