Electronic – arduino – Help connecting custom ATMega328PB using serial FTDI

I built this ATMega328PB circuit.

It runs at 3.3v from 1.5v battery using booster and 8MHz from external resonator (CSTCE8M00G52A-R0).

Using USBTinyISP I set fuses: Low-FF (for 8MHz), High-D8 (Boot Reset Vector Enabled), Ext-FD.

Using VisualStudio and vMicro plug-in I compiled a program for UNO. vMicro created a HEX file of my program WITH a bootloader which I uploaded over ISP and it runs well (blink the LED).

My final goal is to make a customized 8MHz bootloader but as intermediate steps
I am trying to get a sign of life over serial using FT231X FTDI, and than upload a sketch over it.

I cut the 5v jumper on FT231X and connected 3.3v jumper instead.
Then connected (without a battery):

ATmega328   FT321X
---------   ------
Vcc         Vcc 
GND         GND
GND         CTS
RST         DTR (over 0.1uF)
RxD         TX
TxD         RX

Since the default UNO bootloader UBRR register is set for 16MHz, I initialize it manually and try to push data over serial.

#define myubbr (8000000/16/9600-1)
void setup()
{
    pinMode(6, OUTPUT);
    // Init serial
    UBRR0H = (unsigned char)(myubbr >> 8);
    UBRR0L = (unsigned char)myubbr;
    UCSR0A = 0;//Disable U2X mode
    UCSR0B = (1 << TXEN0);//Enable transmitter
    UCSR0C = (3 << UCSZ00);//N81
}

void loop()
{
    digitalWrite(6, HIGH);
    delay(100);
    digitalWrite(6, LOW);
    delay(100);

    char * str = "Hello World";
    while (*str) {
        while (!(UCSR0A & (1 << UDRE0)));
        UDR0 = *str++; //send the data
    }
}

On the PC I run: avrdude -v -p m328p -c arduino -PCOM8 -b 9600

Avrdude recognizes the correct com port but gives:

avrdude: stk500_getsync(): not in sync: resp=0x00

The RX and TX LEDs on the FT231X never blink.

I don't even know if the problem is HW or SW. What am I doing wrong. What else can I try?