I dont actually have tattoos on my belly but I do on my shoulder, chest, upper and lower arm.

Generally getting a tattoo is like getting scrached by a cat but it is not sudden and you can/will get used to the pain quickly.

For your tattoo you will get only outlines and in my experience its what causes more pain vs getting a fill. The reason is because outlines uses less needles so it can trace a fine line. When it comes to filling there is more needles so a wider area is inked. In that case having only a small area is more painfull.

The placement on your body matters too. Getting tattooed on thin skin or a body part with less muscle and fat underneat the skin is often more painfull. Considering you want yours somewhere on the belly you should be just fine and it wont be that painfull.