Gums bleeding on their own is absolutely a thing. But that's usually when they're in a fairly advanced stage. If your gums ain't bleeding then you should be good.
I don't have much experience with cavities aside from one time when I was around 10 or so. Wound up having 8 of them, and this happened without any pain whatsoever on my part. Just cause you don't have any pain or discomfort doesn't necessarily mean you won't have cavities.
Cavities are asymptomatic until you need a root canal, at least as a rule of thumb. It's harder for a dentist to spot them sometimes, even moreso for a guy looking for them in the mirror.
Here are two examles of cavities on the left walls of the two premolars, you can hardly see them even in this picture (you have to look for a brown/dark shading coming from inside the teeth):
You still can notice the brown discoloration of dentine, which is the inner tooth material, in the second picture, showing you the decay was advancing and reaching the part where the nerve and pulp are located. Those teeth are completely asymptomatic until it gets close to the nerve and pulp and at that point you can remove the cavity, disinfect the portion near the pulp chamber and hope that the restoration, being so close to the pulp and nerve, doesn't cause an irreversible irritation of the nerve forcing the need of a root canal treatment.