Hello! Congrats for your second baby, I am sorry to hear you feel overwhelmed but let me tell you: you are 19, you have a 1 year-old, you are living with the dad and also you pay your own bills, sorry but you are not a disappointment! I say I admire your strength and the decisions you made, and I think you'll just get over this one too.
I hope you can find a way to still go to university, I would say pushing the wedding back is not so critical, but then again I'm not married and also expecting (living with the dad too). I will pray for you and your family so that you'll find a way to manage everything you are expecting, sooner or later :)