Titles are arbitrary organizational constructs created by the company. What is "Lead", "Principal", "Senior" is different from company to company.
Given your years of experience alone you may fall under a "Employee Lv. 2", a "Employee Lv. 3" or a "Senior Employee" -- it all depends on that particular companies organization structure. Are you actually leading anyone? If not, you're not a "Lead"... unless your company wants to arbitrarily use the term.
I recently left an employer who described an employee simply on a 1-6 scale. Everyone was a "Software Engineer Lv. 2" or a "Human Factors Engineer Lv. 5". There was no "Senior" and the term "Lead" meant you led people (but weren't a manager).
I now work for an employer who describes lower level positions in terms of 1-3, e.g. "Software Engineer Lv. 2", then tacks on the prefix "Senior" for a level or two, then uses the prefix of "Principal". When I speak to friends and tell them my title, they have no idea what "Principal" means in the context of their world.
If you work for a company, you should not be making up your own title. Without context given to it by the company, it is meaningless (even with context, titles are often meaningless).
If you don't work a company directly (i.e., you are a contractor or you want to put a "title" on your LinkedIn account), then don't give yourself one at all. You are a "UX Developer", or a "UX Designer", "with 7 years of experience".