One of the most important decisions in life is to decide marriage. This decision should be taken only after knowing and understanding the life partner with whom you have to spend your whole life, and should take care of some very important things and move towards this decision.
As far as you are concerned, to marry your father's sister's daughter, you can get married with her. Traditional marriage systems prohibit marriage in a gotra. Still, in many areas of the country, a gotra does not get married, but in 1955 the Hindu Marriage Act was created and all the old customary laws were changed.
Real Brother-sister, uncle-niece, aunt and nephew, real brothers 'children, sisters' children many more Relationships come under the ambit of a Prohibited relationship and if someone marries in such relationships, it will not be valid. According to law , Spinda relation cannot marry. That is, if a boy or girl wants to get married in the 5th generation of the father and the 3rd generation of the mother, then she cannot get married. This is called the Spinda relation. However there are exceptions to the Prohibited relation and the Spinda relation.
But your relationship does not come under their purview because as your aunt is not even real sister of your father, then you can do this marriage with the consent of your family, there will be no problem on behalf of Law