I don't think you are crazy. If you feel ready emotionally and physically then go for it. If I am not pregnant again now then I am starting bc and planning to ttc in a few months.
Aren't you separated from you husband and thinking of divorce? I really don't think given your post on the Single Parent's board TTC should be anything your considered.
Anyway to the OP -- I personally think it is good to get a 6 month break before you get pregnant again simply so your body has time to recover. Having multiple kids is always a challenge but if you want your kids close in age thats fine too.