Hi everyone! I have been trying to post pictures of little Miss Winnie but it says my files are tok big

but my question here is about flea/heartworm prevention. I have two different vets for our animals. They all go to both....and both have recommended trifexis or revolution for our household because our weenie dog has severe (I mean SEVERE) flea allergies. Our two older dogs are on trifexis and have been for a while. The kittens are on revolution. Winnie is now 12 weeks and just hit 2# so its time for her to get her shots today and I would really like to start her flea/heartworm prevention.....I worked for a vet for 6 years and heartworm scares the bejeepers out of me....and keeping her flea free has been a chore. But i have also been a stay at home mama for the last 7 years so my inside line to info isnt there anymore! The trifexis has kept our house clear for so long....but im confused now because of all the new info. I have to wonder a lot of the reports say the dogs died of heart related issues so I wonder did they possibly have heartworms already when they got their dose? That would surely cause illness and death....im just very confused. I know trifexis has been talked about but I was wondering what might be used here. Frontline and sentinel simply sterilize the fleas so thats not an option as we cannot have any fleas in the house for Chloe. They must be dead. Is revolution ok for a 2# baby? Does anyone have experience on what to use for our babies when one has a flea allergy?