Hello Leggylad and welcome to the forum.
I hope you are reading some of the other threas here, you will see a lot of stories similar to your own. You will also see some of the success stories – what are they doing that you can apply to your own situation?
Why do you keep doing it? Well it’s a simple answer for a complicated problem – it’s an addiction.
Where do you normally gamble? What barriers can you put in place?
Try and speak to your girlfriend.. This time though don’t just tell/promise her you are stopping – show her by your actions what you are going to do to deal with the problem. Show here this site, she will see you aren’t the only one with the problem and she can also get support and advice for herself if she uses the Friends and family Forum, make yourself accountable so that you can’t gamble in secret. Trying to keep things hidden can in itself send someone gambling as they try and keep hidden debts secret.
Maybe try those Ga meetings, again how can you get to a meeting each week without telling your g/f where you are?
Keep posting and let us know what positive steps you are taking.