Um, try googling homeschool preschool. I bet there will be some ideas for indoor creative and sensory play. They had a sand table that would morph into a water table after a month or so and all sorts of other textural activities at my kids preschool. Along the same lines, I used to strip mine down to a diaper, put a sheet on the floor and let them finger paint to their hearts content and just throw them in the tub after. It was mostly just squishing the paint around, the way it felt in their hands and on their bodies, that was interesting.

Also try rotating toys. Put a small box of toys out. When she tires of those, put them away and take out the others. That way something is always "new". Also makes tiding easier since there is less junk to get disorganized. And stuff that is not typically called a toy like a magnifying glass can start to be fun at this age with proper supervision.

I wouldn't worry too much about not having too many other kids around at this age. From what I have read, kids don't really start to develop social skills until they are three. Before that, preschool is mostly either daycare or mother's (father's) day out events. She will get every virus known to mankind for a bit once you around more people since she has been fairly sheltered.

Here's a list of things we did when short on cash and toys:

Make music/noise with kitchen stuff, like banging on pans with wooden spoons and making instruments out of containers and beans. We had our own band.

Sensory: playing with rice in a tray, cornstarch and water, putting pudding in a ziploc and drawing in it, sand in a bucket, etc.

Dancing to music. That's fun (and tiring...).

Water play outside and in the bath.

Eating meals in unusual places, like a picnic in the living room.

Going "camping" by making a tent with a sheet over a line in the living room.

Reading, reading, and more reading. We worked with books probably two hours a day, some days.

Do everything in short chunks, so she doesn't get bored and things seem fresh. I like the idea of putting toys away for a while, as it also works well with older kids.

Even cleaning up can be fun: put on music, dance & sing while you sweep, do laundry, etc.

Here's a good site with cheapo ideas:

http://handsonaswegrow.com/50-toddler-activities/

This is a developmental age where you want to provide a lot of sensory experiences: touch, sounds, taste, color, and so on.

Have fun! I echo the other poster: don't sweat it that you're not around other kids her age. There's plenty of time for that kind of play, when she's older and more into it. By hanging out with her so much, you're giving her a head start on advanced vocabulary, early literacy (lots and lots of reading time), and a sense of comfort and safety.