Confusing feeling

I have a 19 month old and a 5 month old I want to start trying for our third in March and my husband wants to wait till August. It took 5 years and a few miscarriages to have our first. I’m nervous that it will take awhile to get pregnant again. I don’t want any longer than 2 years between kids. I feel crazy for wanting to get pregnant again. My sister in law is pregnant so i don’t know if part of wanting another baby is because of her being pregnant.