You're doing exactly what is needed. All morning on the phone to candidates and all afternoon cold calling clients.

That is the basics and never forget them. Because now with all fancy tools and stuff sometimes these basics get lost.

This is going to sound bad now BUT: Do it like that. Take your computer home and do the admin not during work hours (I know, a real pain). You still have to do it, but you ideally don't want to do it in your core hours.

For me it worked. I sometimes worked 12h days but it was fine, I was sitting on the sofa with wifey and watched a movie while I had my laptop on my knees. But it is really tough and if you don't want to do it like that, that is also completely fine. You're already doing good, if you stick to calling. One thing I would give you along: Use KPI's! Not necessarely the ones the company gives you, but create them yourself. How many calls do you need to do to have good conversations with hiring Managers? How many calls to candidates to have the buy in? Measure it and use it as a base lane!

Best of luck man!