Hi there - I also got pregnant with #2 when dd1 was 10 months old. I did find that my milk dried up quite a bit, but not until dd1 was 14 months old.
Not ideal, I know, but at least my milk supply stayed OK until after her 1st birthday. As my milk supply decreased, though, she just naturally stepped up her eating. Children know when they are hungry, and I'm sure you're ds will also make sure he eats enough.
DD1 also continued to nurse throughout my pregnancy, and she's still nursing at 3 1/2 years old (along with dd2, who is almost 22 months). Although it can be difficult at times to nurse through a pregnancy, if you are committed to it, it is definitely possible.
There are some things I regret (for dd1) about getting pregnant so soon, but I think there have been many compensations for her as well. Both of my dds love each other and play so well together now. I'm glad that they are close together and will very much grow up together. DD1 never remembers a time without dd2, so there wasn't a lot of jealousy (some unsettled sleeping for a month or so, but that was about it, that I remember).
You're little one is still a baby now, but he will be a toddler when his sibling arrives...he still has you to himself for the next 8 months or so.
Congratulations on your pregnancy.