Some grandmas brag about their age instead of hiding it. Every year they got is a year they earned. Borrow that attitude.

Hiding an age treats having lived as a problem to be managed. The alternative is to treat each year as something survived and earned, which is accurate, and it tends to produce people who are much easier to be around because they are not spending energy on a pretence. The attitude is available to borrow at any age, including yours.

Notice where you already apologise for being new, young or inexperienced. Try stating it plainly instead: you have been doing this a month. Plain beats embarrassed, and nobody minds the honest version.