PIP backpay question, worried about being overpaid/in debt to DWP

hello, first time posting here. i received my first PIP payment today which i can only assume to be backpay - approx £1900.

for reference, my claim started 22nd may, awarded 2nd august, standard daily, enhanced mobility.

the thing is, when i called about 5 days ago to ask about my payments the day it was awarded, i was told the backpay would be in £500 instalments, starting from the end of this month.

i have left a message on my UC account asking what i want to ask this community: have i been overpaid? i am worried that they sent too much and that i need to send some back, because £1900 seems excessive of what i expected the backpay to be. can anyone else tell me how much their backpay was, and when they got it?

thank you for any help!