risks and safety

[SadisticSara]

Yes, permanent damage CAN be done even if it doesn't hurt that much.

With livestock, they just jump at first from the rubber ring being snapped in place around their ball sack (when an elastrator is used).

After that, their testicles soon go numb. No pain.
The animals continue eating, walking around, and acting normally. But the cells of the testicles "die" because of lack of blood supply. The longer it's on, the more cells that die. It's not sudden, like surgical removal of the testicles. There are different degrees of damage.
Ditto for humans.

Weight gain is also one of the symptoms of testicular damage. But weight gain can also be caused by many other things.
Another symptom is your balls being smaller than they used to be. But that can have other causes too.

I can't diagnose you online or give you medical advice, other than to repeat my recommendation that you see a real doctor.
It wouldn't cost much and there's no reason you should avoid seeing a doctor.
Doesn't have to be a specialist. A General Practitioner can order the simple blood test.

I can't (and shouldn't) try to guess about whether any permanent damage was done or not. Seeing a doctor about it would at least stop you from worrying about it, no matter what degree of damage (if any) has been done.

Read the previous posts again. Then make an appointment to see your doctor.

PS. I think that a blood test done by a medical lab at your doctor's request would be more reliable and accurate than a saliva test done by mail. But I'm not a doctor and I'm not qualified to give you any medical advice.

That link you posted to that saliva-testing company also talks about "anti-aging medicine". Ummm... I don't think I'll even get into my opinion about that!
Please see a doctor.