weight

My 1.5 year old spayed female seems to be thin. We got her recently from a shelter. I have her papers, she was just vet checked about 2 weeks before we picked her up. This is what the papers say:

All vaccinations up to date, spayed, advantage flea control applied, dewormed w/ Nemex tabs.

My question is this. I know she was dewormed, but is it possible she could still have worms?? I checked with the shelter, and they said she was dewormed two times in the 3 months they had her and never had any medical problems. She isn't "really really" thin, but seems a bit smaller than my other female. She is probably about 8lbs versus Sunshine at 10lbs. When you feel by her hind legs she is "indented" much more so than Sunshine who has a small layer of pudge.
She seems very normal, eats well, drinks well, litter box is fine, behavior is fine, her coat looks good, and she has no vomiting or diarrhea. Is it possible for her just to be naturally thinner?? Are there other symptoms I should perhaps look for before rushing her off to the vet ( I paid for her vet bill when I got her from the shelter so I am hesitant on blowing another $40 if its nothing, especially since she was just there about a month ago ).

Thanks for any responses.

The easiest way to tell, is to feel for the ribs. If they are showing then she is probably under weight. Most cats male or female have MUCH different builds. I have a female who weighs 9 lbs at best and another who is closer to 15. If she is eating, drinking, sleeping normal I wouldn't get alarmed.

My female 3 yr old (spayed of course) is a healthy 8 pounds. She was just at the vet too.

But if you are concerned, tell the shelter! Tell them you want to bring her back in because you are not sure if she was properly dewormed. Since they said they did this, and you paid for their vet services, you should be satisfied. Moreover, a good shelter is concerned about the health of the animals they adopt out, as well as the happiness of their 'customers'.

My cat was de- flea-ed (how on earth do you write that?) at the shelter. Yeah right. Took us months to get rid of the fleas he brought in.

Thanks Alicat and Sandie.

Alicat, actuall the "shelter" is just run by a woman in my town who takes in abandoned and strays and then adopts them out for a "donation". I donated the cost of her vet care that she had from the 3 months that she took care of her, which was to cover all vaccinations, deworming ,and spaying. She is the only local shelter that is near me, but is not an actual official "shelter". Anyway, I contacted her and she said that she has no knowledge of tapeworms, but that my cat was dewormed for round worms. I am thinking that Sandie is right. She has NO other signs of anything wrong other than her seeming a bit thin. And I looked at her rectum and don't see anything that resembles grains of rice on her or in the litter box. So I think I'll take the wait and see approach unless she starts showing any sort of other symptoms. Thanks for all of your input.

Daniela - I have been wondering about Smudgie as well being too thin. The rest of my cats are all tubs yet she only weighed in at 5.9 pounds this week when she was spayed. Her brother Rip weighed in at 11 lbs. They are 9 months old now. Maybe we just have two little petite babes?!?