Am I crazy for considering this?

I had my third baby 5 months ago. I am a 23 year old nursing student and my fiancee is a cdl driver. We have talked about 1 more baby. I want one and we said it's either soon or years down the road. Because once I graduate we will be focusing on buying our first home and everything that comes with it. So I have 2 1/2 years till I finish my degree and I am considering once my 3rd baby turns one to try for another then call it quits. I am excited to think about it but nervous and everything that comes with it. I don't know if its baby fever taking over me and If i should honestly wait until i own my home but we are taking 7 years down the road. I have always wanted a big family. My oldest will be 5 here soon and my middle baby is 3. Am i crazy for thinking about this or should i take a step back and really think about all of this?