I'm 19 too, first time though so you have that on me lol
I'm sure you'll be fine, you're in a good situation and you've already raised a child, I'll cross my fingers that your family are excited for you :)
Congratulations! If you've already had a baby, you're in a stable relationship, and youre financially stable and all that, then hopefully your family will be happy and excited for you. I hope you get your wish and have a girl this time. Just remember that your situation is good, and that a lot of girls have it so much worse, and if your family objects, remind them that you're in a good place and really emphasize how happy you are to have another child.