Helppp!

My first born will be 2 on October 23rd and I currently have a 4 month old son. In all honesty getting pregnant so soon after my daughter came as a surprise and I was very worried at first. My son hasn’t been an easy baby (dealt with colic, then eczema & he’s not doing well with teething). Most days are beyond hectic. My husband has a decent job I’m still in school trying to become a nurse which best case will still take 3 yrs. I’m pretty sure I want a 3rd baby and part of me would love for my second and third to be as close as my first and second (17 months apart. Am I crazy to consider having 3 under 3 while going to nursing school?? Will a 3-4 year age gap be dramatically different than their 17month age gap!? Thanks in advance for any advice.