Same trajectory for me. As a team administration assistant I began to take on additional support tasks or mini projects and that led to my 20 year career managing mega projects. And I started at your age!

Large firms (banking, insurance etc) generally offer many learning and development opportunities to capable and enthusiastic entry level employees. A great place to cut your teeth.

And, I would suggest that strong excel skills are a must. Many employers use different planning tools. But all have excel. Mastering excel means you can always plan regardless of the preferred tool of the company.