Help!!!

So I am usually irregular ever since I gave birth to my youngest. Well I usually dont go past two days late and we'll today marks day 3 almost day 4. I have a thick white discharge that has been there for about a week now and its similar to the discharge I had when I found out i was pregnant with my middle child. I don't want to be pregnant again just yet my youngest is almost 8 months and she has alot of medical problems and she needs a lot of attention that if I do have another baby she won't get.

Any advice?? I am 22 years old btw and I was raised by my father never had a mother figure to tell me anything.