I got pregnant when my first was 6 months old. We were NOT trying at all. I was breastfeeding full time, but she was sleeping through the night and we did one formula bottle a day as well. I think there isn't much you can personally do to make it happen. Just varies per woman and cycle.... However having sex is key :)
I never got my period before getting prego. I just happened to get pregnant the very first month an egg was release and since my husband and I had been back at it for months and months, his boys were just in the right place at the right time to meet up with the egg. So just relax, have fun with your husband and what will be will be. Your body knows best.
BUT I did want to throw a few things out there to think of..... because having 2 so close, while wonderful, as can be SO tiresome!
First breastfeeding while prego is VERY hard and painful. My milk pretty much just dried up and it must have also tasted different, because my daughter was just over it! It was sad because we still had so much more time to go. My doc also didn't recommened it. It does make the uterus contract and it takes so much calories from you! I couldn't eat and drink enough to keep up.
Second once the baby is born it can really be hard balance it all. Two little ones who need you so much is crazy at times. And although your baby now is sleeping well, your next probably won't be as good. My 2nd baby (now 8 months old) still does not sleep through the night, while her sister ALWAYS did. I am up at night with her so much, but I also have to be up bright and early for my 1st little one. I am tired ALL the time! And napping like I did with the first is not an option!
Third, just taking care of your baby while prego is interesting to say the least. My back hurt so much because the baby will sit so much lower since the uterus is still pretty stretched out. They want to be carried and boy does that belly get in the way. As I got into my 3rd trimester the back pain actually went away, but I just never felt normal and could hardly keep up with my little girl. I want to point out I am small, thin and in shape, so it was just being pregnant that got in the way. I would even fall asleep in the middle of playing with her! That is how much it zaps you!
Fourth is the fact that I feel like I cheated my 1st child out of our time together. My husband and I admit that we feel like the two kinda meld together in our minds. We nearly can't remember who did what at what stage or just little fun memories like that. I am not saying is bad, but you just have to learn to pass the love around and having that special one on one time isn't as easy to come by right now. Maybe as they get older it will be easier, but as babies it is just hard.
I also feel like my 2nd is getting cheated as well. Breastfeeding hasn't been as enjoyable because I can't just sit and relax like I could with her sister. The older child needs you all the time and when they are mobile and you hear a crash somewhere in the house or they gotten into something they shouldn't ect, you have to unlatch the baby and run to see what is up. That happens often and she is really a good girl. I can't imagine if she was a naughty kiddo. My only relaxing time with our 2nd is in the middle of the night. She is self weening right now and I think it is because she is just over it :)
Plus we don't take as many pictures, she doesn't get all the cool new toys, because big sis get them all first ect... I know that is an issue with most sibilings, but it just seem worse since there isn't much space between them.
I wouldn't change how things happened for us at all, but I am frazzled most of the time. Not sure how I juggle it most days. Going to the grocery store or just anything outside of the house is a total production. Again my little ladies are well behaved, but it is still a handful. Just think of the how to's with 2 kiddos when out and about for a second. As they are getting older it is getting easier, but those first 6 months after #2 was born are like a blur- not even sure I brushed my teeth most days. The house is always a wreck, but full of laughter :)
It sounds like you have a supportive husband, so that is good! I could not have done it without him at all! But on days when he isn't as helpful, I for sure have bad days and can even be brought to tears over nothing....
So my point is really to just think it over and make sure you aren't going to take away from your little one right now. Also give your body time to heal up and get what it needs back.
While we are over the moon happy with our two girls I will point out that my husband got a vasectomy when #2 was about 3 months old. Having two so close was just more than we could handle mentally and so we just couldn't risk another close pregnancy! That makes me sad because I feel like if we had spaced them out better, perhaps we would have wanted a 3rd baby at some point. I still struggle with that. And while I couldn't imagine having another one right now, I just can't shake that feeling like we might have felt different if things had gone different for us.
Anyhow good luck! But please take in baby #1 now, while you can.... it goes so fast!!! It takes my breath away... :(