3 of 5 added info about problem's origin and an attempt to solve it

DFA, lower bound on number of states, language with primes and remainders

This is an exercise from old exam on formal languages that I don't know how to solve:

Let $p \ge 5$ be a prime number and $L_p$ be a language of words over $\{0,1\}$ that read in binary from right (i.e. from least significant bit) give a number that gives remainder modulo $p$ from the set $\{1,2, \ldots, \frac{p-1}{2}\}$.

How to show that:

Every DFA recognizing $L_p$ has at least $2p$ states.


One fact that I know of and is somehow related (has DFA and primes in the statement) is:

Any DFA recognizing language $\{0^n : n \text{ is not divisible by } p\}$ has at least $p$ states.

This can be seen by observing that the language is infinite, hence any DFA must have a reachable cycle, from which some accepting state is reachable. And if that cycle had less than $p$ states, then because any number smaller than $p$ is coprime with $p$, we could loop sufficiently many times in that cycle and arrive at the aforementioned accepted state with a word $0^{kp}$ for some natural $k$ - a contradiction.

Maybe it's possible to use this fact, or alter this proof somehow to make it fit for the theorem with $L_p$?