Spayed ? dog having pups how soon obviously the vet was wrong!?

ok first of all i must explain how this happened in the first place we got a beautiful westie from a neglectful situation about 5 yrs ago she was 2 then and in bad shape the people we rescued her from said she hadn't been fixed and had lost a litter of pups arounda yr of age so i saved up the money and took her to the vet for a check up and to schedule her spay surgery well i mentioned to the vet i had yet to see her come into heat and since teh previous owners had lied to me about a number of things the vet decided to shave her and look for a scar to see if she had been fixed sure enough there was a scar the vet decided that she was in fact already fixed so we never did the surgery there was no point well anyway 5 yrs have now passed and still have never seen her in heat so never assumed for any reason that the vet was wrong well long story short i noticed a few weeks ago she looked overweight so i cut back on the amount of food i was giving her well the other day i had to help her up our front porch stairs and i noticed she had large nipples so i felt around and i could feel puppies moving i about hit the floor i could not believe this was happening i had never had ANY intention of breeding for any reason i am trying to figure out when she may have them i am a stay at home mom but have a number of dr and threepy apts for my 4 special needs kids i want to be there when she has them i am worried she may have problems due to her age she is 7 or 8 now also i am now worried she may have had a c- cection when she lost her first litter of pups if indeed that is what happened i took her temp today it is 99.6 yesterday it was 100.2 not sure if this is enough of a dip in temp to signal labor or not also yesterday i lifeted ehr up the stairs later and my had got what i think may have been her mucus plug all over it it was clear jelly like stuff about a half dollar sized amount today it is like a minute amount of clear not much at all i have the floor in my linnen closet all ready for delivery have supplies ready and i talked to the vet who is prepared for any complications she is up to date on all vaccines and recieves regular care does it sound like we may have tehm soon i am soo worried about her i talked to the vet and she will be getting fixed as soon after the birth as possible i never want this to happen again and i have a number of very responsible people in our family and a couple close friends who are going to adopt the pups when they are ready a couple are willing to start paying for their vet care from birth on i know they will be in wonderful homes is there an increased risk due to her age i have read everything i can get my hands on since i found out and feel ready i know it is different but i have delivered horses cows goats sheep and helped when my neighbors cat required help to birth her kittens so i do have some idea how to assist if necessary is there anything else i should have ready or know i have never had this happen before and am never plannin g on it again just wish i had known 5 yrs ago that she was in fact not fixed but i guess i had no way of knowing and no reason to suspect other wise any advice will be helpful and yes i did get info from our vet but wondered if there was anything else i didn't know about it never hurts to be as prepared as possible thanks for the help oh and i forgot to say i started her on good quality puppy food once i found out and she has a large bowl of water available at all times also wondering ehn to deworm and deflea her again afraid of giving meds while pregnant when is a good time to reapply her frontline and deworm her again thanks