Not too large at all. Your designer gave you good advice.

i agree. plus the glass will give the illusion that they are hardly there, so they will not over power the kitchen. Perhaps your designer is suggesting another part of your kitchen be the center piece. i read several places that glass pendents will allow for this. Best of luck. in the middle of a kitchen design myself so understand all the decisions involved.

Here is a few good articles about pendants that are helping me.

https://www.drivenbydecor.com/height-pendant-lights-over-kitchen-island/

https://www.delmarfans.com/educate/home-pendant-lighting-guide/#number

https://carlaaston.com/designed/how-many-pendants-should-you-hang-above-kitchen-island-two-or-thre

If your having trouble and feel a little ovewhelmed by your project, here's a little guide that could help you out with making some of the tough decisions. https://www.electricuniverseca.com/how-to-plan-your-next-electrical-project-step-by-step-guide/