Tax woes in august!!

[KingstonMom]

I stated daycare last April. Came from a corporate retail background, so, being naive, I didnt know that I could claim anything, had to issue receipts etc.
I had 3 families start with me, 2 of them stated from the beginning that they 'are not looking for receipts' (which to me, meant that they wanted 'lower-cast' daycare and wanted to save a few bucks opposed to the p[ricier daycare up the street that issues receipts. I had no quams, and so took them all on. All of them knew I was not issuing receipts. (I was also charging a PER HOUR BASIS! At $27/per day. Cheap!!

After discovering this forum, informing myself, and getting my s**t together, I developed a contract, and new families that I took on in August and November were on this new contract and paying $32. My families that started last April also signed on starting January 2012. They knew the changes were: my rate went up $5 per day, now charging for stat holidays and sick days BUT I am now issuing receipts. All was great.

Come tax time, one of the moms (shes a sweetheart, nice, and pays on time, kid's a doll etc) asked me to clarify if I was giving receipts or no. Shes fine either way. I straight up told her no, because I was charging so little and had just started up I hand planned on it. She said no problem, thaqt was fine. Okay, good. I file my taxes, only claiming the income from those kids I had receipts for and only claiming expenses for food to those kids as well.

Now, TODAY, she texts me and says she is just NOW filing and the daycare expenses would have a huge impact on her return. ($500+) She asked me straight out :"is the reason you did not give out receipts is because you did not claim the income?" (Sounds like she was coached by her tax lady right there, doesnt it? lol).
I explaiined to her what I just explained to you all, I had no idea I could, I was charging less, and all that. But quickly said that I will prepare a receipt for her to pick up this evening. told her I will do an admendment on my taxes and its no problem, she is entitled to it. (Which she is)
Im just a little peeved, how could she be so clueless all those other time she was aware about no receipts, but just NOW, IN FREAKIN AUGUST does she mention it. Of course im not going to stiff her, but it just irks me.
I need to go back and change my taxes now? like wtf!?! arggg!!