Low blood pressure is NOT a symptom of HIV.
you have a three month conclusive negative result.
Without some further explanation, I am not sure anyone here will be able to assess your HIV risk. My guess is that you had no risk, but, if you would care to share the details, I am sure that some knowledgeable person would be able to help you with this.
Just for the record, no, low blood pressure is not a symptom of HIV that I have ever read about or heard of.