Glad you are seeing the anxiety piece of this and will work on it. That's the key.
I am not sure where would you come across such information on the internet. However, there is absolutely no risk for HIV transmission from a dildo, neither there is scope of transmission nor there has been any documented case in the history of HIV for someone to get infected in that manner.
Yes. Actually, you never needed to test for this. The only way that adults get HIV is from having unprotected vaginal or anal sex or sharing IV drug needles. Oral sex does not transmit the virus. Enzymes are in saliva that inactivate the virus as well as air inactivates this. So, receiving or sex won't result in getting HIV. And a dildo used in the anus won't either. That is exposed to air. So, you had zeo risk from your exposure. You have now tested negative twice which is fully expected given there was never a risk. You don't need to test again and should believe you do not have HIV. It's okay to worry a little here nd there, we all do but if it is a big issue like always worried or it interferes with life in any way, then it may be health anxiety or general anxiety and you could talk to someone about that.