Two under two!

Any women have two children under 2. I have a one year old already and have just found out I'm pregnant with my second. Due in February:) which means my first child will be 19 months old when my second is born. 
I will only be 20 years old when my second arrives. 
I must admit I am so happy to have two children, but I am also scared to be so young with two children under 2. 
Any advice any mums could give? X