This is a great question. There are two really important things you can do for her.
One is to TALK to her. There was a big study done about vocabulary, and the researchers found that if a child's parents say about 600 words an hour to her, by the time she gets to kindergarten she will have a vocabulary of 2,000 words.
Sounds good, right? They also found that if a child's parents say 2,000 words to her an hour, she will have a vocabulary of 22,000 words by the time she gets to kindergarten. Which child do you think will be more successful in school?
(More about the study -- it's in a book called Meaningful Differences, by Hart and Risley, and what they found is that children in homes where the parents are in poverty hear far fewer words, questions, or affirmations than the children in working class homes, and children in homes where the parents are professionals hear the most words, questions, and affirmations, and end up with the largest vocabularies.)
Your income is not your destiny, however, and all parents can make a difference by talking to their children as much as possible. Talk to her about what you are doing, where you are going, what you see, etc. Ask her questions and listen to her and let her talk, too, as she gets older.
The other big thing you can do for her is to READ to her. Start taking her to the library once a week. Go to storytime, then hang out in the children's section and stock up on good books. Read to her at breakfast, and at nap time, and just for fun, instead of just at bedtime. My boys learned the alphabet when they were two and three, from their ABC books. They learned their numbers and shapes the same way, and they learned tons of vocabulary from all the fiction and nonfiction that we read.
Good luck!! You sound like a terrific mom.