Adopt 2nd Child? Age & Finances vs Single child

We are extremely blessed parents of a wonderful little 15 month old aa son. We couldnt be happier and give thanks every single day. Our only concern is whether or not to try again in a few years. Our son is the only african american in our family....our family has all embraced our son and he experiences loads of love from all, but still......we wonder. We had to go (deeper) into debt for this adoption, and would have to wait until he is in school because we could not afford to have two children in daycare....I would be 46 then! I'm willing to be tired if it's the best for our son, but we wonder if thats unfair to the children. Also, if we just have our son, we can afford small vacations etc., but adopting again would mean living very tight, no trips etc. Again, we would be ok with that for ourselves, only want what is best for our son (and future child if thats the direction.) Any input would be GREATLY appreciated! Happy Holidays, kva