Baby fever

Ugh so a little back story. I have a 3 (almost 4 year old in about 2 months) and a just turned 1 year old, and I'm pretty much raising my 9 year and 3 years old nieces, and 8 year old nephew, but I'm having baby fever something BAD. Mind you im only 18 (i have my own house and car. My parents dont help with anything except for my nieces and nephew every now and then) and i know that right now I'm am in no shape to add a new addition to the family because of all this. But I just feel this yearning for another baby. I guess this is just a rant to let things out. (Ps I have an iud with no planning on removing it)