My son is 3 and I have a 3month old daughter and we found out on the 1st that I'm pregnant again. Adding a second wasn't really hard I already had the experience of dealing with a baby and when we told our families we were expecting again this soon they all took it really well. If you don't rely on any of them they can't really say much its your life. Be happy! Try not to stress too much. You will figure it out.
My second child was actually a lot easier than my first. When I got pregnant with her, my oldest was just after a year old and I was a full time student in college as well. It was difficult but I made it work. Just focus on your classes andif your due before the next semester ends then try to see what it would take to finish the classes a little early so that when you have the baby youare out of class for the summer and that will give you time to get used to having two kids and time to get into a schedule of how to make school work while having a newborn and toddler.
It isn't really to soon I have a six year old I had when I was 17 I have a one year old an Im due a few days before her birthday with my baby boy yes it may seem overwhelming an also my fiancee passed away in June of this year sometimes I get annoyed with my kids I yell an all but I wouldd not change it for nothing in this world an it is OK to especially if your toddler already is walking like mines has been since nine months an she does alot of things on her own its so much us mothers have to do but a mother's job is always a full time job as well keep calm it will all be ok