Kinda upset. Hope I did the right thing.

So 7 weeks ago two mama cats had kittens a day apart. 10 total. They have been in my basement for 6 weeks, and are all doing fine. Don't think the mama's got pregnant in the one week they were outside from giving birth to when I took them inside. I know another female cat I was feeding seemed pregnant, and I tried to catch her a few times, but she would always run away. Today I looked outside on my back porch and I noticed one baby kitten that must have been born yesterday or early today. It seemed clean so the mother did take care of it for a bit. The thing is I did not see the mother in the tarp outside today. I went to the petstore to get KMR and a bottle just in case, and when I got back I still did not see her around. I tried bottle feeding it, but I've never done it before and it did not seem to be working, so I tried to introduce it to the mamas downstairs who are still nursing, but weaning the kittens since they are eating solid food as well. They didn't seem interested. So I took the kitten to the petstore again, because they had an adoption thing going on today, and one of the ladies running it said she would take the kitten and feed it. When I came though that is when I saw the mama cat looking around the tarp. She left for a bit, then came back again, and slept on top of the box she had the kitten in. I know in the long run if the kitten survives I did do the right thing, because it will find a home now, I'm just unsure because it looks like the mother did not abandon it, but was just out and about. I hope also the mother does not have anymore kittens. I know cats usually have between 3-5 but 1 is not unheard it. This is her first litter as I know she was born last year. 

You did what you could in the position you were.  Especielly as you didnt saw no mama although you looked after several times.

A tip: with tiny kittens it is easier to begin with a dropper, or a small syringe. Corner on the mouth, tummy down, head a little up.

Good luck!

Normally the mother will not leave a kitten that young unattended.  It's possible she had more kittens on the tarp and was moving them to a safer place and this was the last one, or maybe she had others that didn't make it and moved this one to the tarp because it was the only survivor.   If so, she'll go the them shortly, and at least the one you turned over to the pet people should have a good chance.  I have raised them from newborn before.  They turn out well physically but often have some psychological problems, so maybe she will find another mother with young kittens and be able to add it to that litter.  You did the right thing, and if nothing else, the mother cat will learn not to leave newborns alone for very long.