Trim the text exercise - C

[HelpMeC]

Hey everyone.

This is the description of the exercise:

Write a function that receives a string and prints a "trimmed" version according to the following rules:
1. All consecutive whitespace is reduced to a single space: spaces, tabs and newlines are removed and replaced by a single space.
2. All words have the first and last letter removed. A "word" is any sequence of characters that is not whitespace.
Example:
trim_text("some text with a space$$");
should print:
om ex it pace$
The function signature is: void trim_text(char * str)
Hints: You may use "isspace()" found in ctype.h (already included for you).


Here is my solution:

void trim_text(char* str) {


    size_t size = strlen(str);
    if (size <= 2) { // The trimmed string is blank
        return;
    }


    char* trimmed = (char*)malloc(sizeof(char) * size - 1); // Without the first and last chars but with null-terminator
    int currIndex = 0;
    str++; // Let's iterate the str from the relevant first char (second one as the first is trimmed)


    while (*str != '\0') {
        if (isspace(*(str + 1))) { // Then this is the end of the word - trim it!
            str++; // Now it points to a space - and we'll increment it to the next non-space char
            while (isspace(*str)) {
                str++;
            }
            // Now str points to the beginning of the next word
            if (*str != '\0') {
                str++; // We have to trim the beginning of this new word
                trimmed[currIndex] = ' ';
                currIndex++;
            }
            else {
                trimmed[currIndex] = '\0'; // The trimmed str is ready!
            }
        }
        else if (*(str + 1) == '\0') { // We are at the end ot str
            trimmed[currIndex] = '\0';
            str++;
        }
        else // We are in the middle of str where the char is not any of spaces
        {
            trimmed[currIndex] = *str;
            currIndex++;
            str++;
        }
    }


    printf("%s", trimmed);
    free(trimmed);
}


int main()
{
    trim_text("some text with  a     space$$");
    return 0;
}

My output is:

om ex it<TWO WHITESPACES>pace$

Whereas the expected one is:

om ex it<ONLY ONE WHITESPACE>pace$

Can someone figure the problem in my code out?
I have been debugging it for a while but I didn't catch the problem...

Thank you.