We used https://microchipidequine.com/ and had no problems with registration or with USEF. Simply mailed the forms in and then received conformation in the mail less then 2 weeks later.
I used HomeAgain for my horse and registered him on their website, so now my dogs and cats and horses all show up on my account and I can be reached if any of them are ever lost.
Thanks all for the input. I will register mine with PetLink since that is where the dogs are registered. Its just $20 and no annual fees.
My chip also begins with 985…so it IS able to be registered with USEF. I read the email wrong and thought ANY chips that began with a 900# were not recognizable.
All of my HomeAgain chips start with 985 and they are permitted by US Equestrian so you should be good 
