I dont have herpes, so what are other reasons i can have blisters at the opening of my vagina?

It's probably herpes: How do you know you don't have herpes? It is very common in sexually active people even when not known to be at risk, e.g. from an infected partner without symptoms. Herpes is by far the most commmon cause of symptoms like yours, but maybe an allergy or severe yeast infection could do it. See a doctor ASAP. Waiting even 2-3 days will make diagnosis harder and treatment less effective (if herpes).