2 years is more than enough for people that are claiming to be "accepting." I think your best bet would be making it clear that using female pronouns is not accepting, as someone mentioned earlier. I agree with others here, it's like they think it's cool and fun to be accepting of you but don't understand what that means or don't want to, they just want to be "in" because people are becoming less and less tolerant of ignorance in present society, so they put in the minimal amount of effort.
For personal example, I have been out to my parents for 4 months, coming up on 5. My mother started trying within a week or two to get my name and pronouns correct, and by month 2 she was golden. She makes a mistake maybe once out of every 200 instances. My dad, on the other hand, didn't start using them until month 2, and still slips up on occasion. It's clear that both have practiced and are getting it down, in not even a quarter of the time it's taken your parents to decide that they are fine with the idea of you being transgender and will support you, but I think yours need a little help understanding that a little more effort would go a long way. If they don't want to put that in, they don't respect you and it's time for action.