Fur mom and vet left very confused.. is she or isn't she?

Hi there.. have a question that I hope someone can answer. My 7 year old cat (whom I got from the humane society when she was a kitten and they told me she was fixed) gave birth to a still born on Thanksgiving morning. I had a feeling she was pregnant because she was getting so big. She is an indoor cat but I have two males that are not fixed yet.. she didn't even show signs of being in heat. Anyway... she had the kitten and we have both been sad since.. I took her to the vet Friday because I could swear I still felt bumps in her belly that would go away after I touched it. The vet did deep abdominal palpitation and said she didn't feel anymore kittens but still could not be certain unless I had an X-ray done on her. Well I did not have the $71 an X-ray costs so I couldn't do it. The vet said since she was eating and looked good not to worry and i made an apt for next week to get her the X-ray.. I told the vet about the bumps I felt and she said that it IS very uncommon for cats to only have one kitten. We both were left confused because she said even though it's uncommon it IS possible for a cat to have a still born and still have other kittens cooking for a few more weeks. Has anyone had this happen? My girl is still pretty big.. and she is aggressive toward the other cats in the house.. so obviously she is hormonal as well..do you think I am feeling other kittens? When she is lying on her side and I pet her I can feel a lump in her belly...it doesn't really MOVE but one minute it will be there and the next it won't..could it be a kitten or her intestine? I just want to know what to expect.. because I may not be able to get her that X-ray.. at least not until the second week of Dec..Christmas time is always hard on me financially so I have to wait til I have the extra cash. She is still following me around.. and although she isn't as big as she was before the kitten was born she still is bigger and wide. She still goes into her closet where she had the kitten.. ( I think it's to check if the kitten is there) it's sad.. she would make a good mommy.. but she stays in my room with me close by the closet and I am just worried. If anyone had this happen please clue me in. Thanks so much.

Yes, its fully possible to have others still alive.  Im a little confused- YOOU flet the bumps, but not the experienced vet.  It depends in much, how old the stillborne was.  But not even this is 100% - its fully possible for them to have two different litter simultaneously, perhaps 3 weeks apart.   Both litter could be happily delivered in their own times.

Yes.. I felt the bumps.. the vet said she didn't feel anything but she said she wasn't positive.. I told the vet what I felt and she said that I could have been feeling kittens...she palpated the very bottom of her abdomen and when I felt them she was on her side. I was just petting her when she was laying down and I felt a lump.. I put my fingers on it gently and it went away.. like popped back into where I couldn't feel it anymore..it's so hard to explain. But I felt it on the side of her tummy.. the vet was feeling her under belly closer to her back legs.. so idk?? I am an RN so I would like to think I am SORT of experienced.. lol.. but I am no vet..thanks for replying..

How old was the stillborne?  almost done, or  a fetus?    If almost done, its still possible there are two different litters.  Not common, but not completely unique either.      It IS unique for breeders, whom have control over matings.  But not that unique among free living cats whom mate as they pleases.

One of my ex neighbours had such a cat from such a second litter.  Taking one example.

The question is, if you spay her now - accepting it may be an abort (early one, they can hardly be almost done even if they are there) - or you wait and see...

And neuter the "naughty" boys.