I don't think you have anything to worry about. My cat does the same thing quite frequently and has done for a long time. We've taken him to the vet a few times but they've always said it's because he eats too quickly. We tend to feed him a couple of spoonfuls at a time and spread his dinner over 3 or 4 instalments. It's time-consuming but it's better for your cat and his teeth!
 
Regarding your vet bills, there are organisations like the PDSA and Blue Cross (UK) that can help you out if your cat ever does become ill. Check out their websites. Please take your cat to the vet if you think she's unwell. There are ways you can afford it.
 
All the best.

 I'm so sorry to hear you are having money problems, because I am going through the same thing right now.  I know how difficult this is.  I have two cats and they do the same thing.  It seems to be normal for cats.  She,s either eating too much too fast, or it could be fur balls.  Cats sometimes ingest hair when they groom themselves and end up vomiting it up.  I don't think you need to worry.  Just keep an eye on her and if it gets worse, you might want to call a vet just to get some professional suggestions.  Good luck with the cat and hope the financial problems get better both you and me.