V.G.
I read your post, and I was wondering why you feel like you have to start weaning?
I would suggest maybe keeping the 2 a day- before nap and I'm assuming before bed. These feedings do wonders for little ones- from giving them extra immunities to that special bonding and secure feeling they so very much need.
Once you go down to 2 times a day- even if you go down to one time a day- you should start ovulating again withing the month.
Even if you're trying to conceive it is still safe and good to breastfeed. :) Millions of women breastfeed through their second/third etc pregnancy and have wonderful healthy babies.
Why not check out a book at the library on either tandem or pregnant breastfeeding. There are many books that are very informational and can give you that support you might need. :)
I believe weaning is a decision a momma and a baby should make together. I'm sure that once you get pregnant she'll probably wean herself because the milk starts to taste differently. Thats what happened with my son when I became pregnant for the second time.
Good luck, and way to go for breastfeeding your little one :)