What if i have a blister and i don't know if there puss inside but i feel like there is when i touch it lightly? is it infected for sure?

Blister: Usually a pussy blister is milky white in color. Transparent blister is usually not puss filled. Also, there is usually significant perivesicular reaction (redness/swelling) associated with infection, however, non pussy blisters may also causes that. If you are in doubt, i'd get seen by a medical provider.

Tender blister: Depending on where the blister is, a dermatologist may determine that this is an infected hair follicle (folliculitis) but if it is from friction, trauma, a burn and is a fluid filled vescile or blister, pain is common without infection. Don't lance or squeeze it as this could cause a serious infection if there is bacteria there. See a doctor.

Compresses: Minor blisters that are not infected can be treated with wet to dry dressings. A slightly wet towel is allowed to dry and will gently detour a blister .Do not pick it open the top layer of skon acts as a biologic dressing until the new layer of skin is ready.