Don't be embarrassed. You're still really young. It may be slightly unusual that you have no work experience, but really not THAT unusual, and you have a good reason. Choosing to focus entirely on your studies while being on scholarship was responsible and reasonable. Having a degree is ESSENTIAL. It won't guarantee you a job, but without one, a lot of jobs are just not attainable. It's great if you can also show that you were summa cum laude. Yes, your lack of work experience may be a disadvantage, but at your age, it's probably a rather small one.

You may not like this next part, but you just need to send your resume out--a lot. I know that's painful because it's never pleasant getting rejected, but if you're persistent, you'll land some interviews. You may bomb a lot of them in the beginning, but you'll improve with practice. Additionally, try to network. It's not the only way to find a job, but yes, a lot of hires happen because you know someone who knows someone, etc. People like to hire employees someone can vouch for. But don't be discouraged if your network is too small and can't help you. It IS possible to get a job simply by applying, even if you have no contacts. It just takes some tenacity.

If it helps your mindset, instead of making your goal finding a job, make your initial goal to get 100 rejections--then 200, 300, etc. Because you can succeed in that without a doubt--simply by sending out that number of applications and (hopefully) a few more! Along the way though, you'll definitely get some interviews.

I also have a BS, then did my PhD in a STEM field, and have experience in academia and industry. So I'm not saying I'm an expert, but I'm familiar with your situation.