I would write this woman an immediate termination letter for not showing up and non-payment of fees, in it I would state any and all fees paid and calculate all monies owing. I would also attach a photocopy of the contract she signed saying she is obligated to pay the above money. Then I would set a date that the money is due otherwise legal action will be taken. Send it by registered mail so she has to sign for it. Don't do any receipts until the end of the year as required for tax purposes.

If she doesn't pay up, you could file in small claims court. I think for that small amount of money that the cost of a lawyer's time may just break even or you might end up owing some to the lawyer, so I probably wouldn't do that myself. I personally prefer collection agencies. While I don't see every penny of what is owed (they take a percentage), they will hound them until they get it. It is also relatively low stress on me since I am not doing the hounding, which might be helpful in the last months of your pregnancy.

Sorry you are having to deal with this.