Adult British Passport application - Documents missing

Hi all,
Am abit concerned and wondered if anyone has experienced same situation as me:-

I applied for 2 adult British Passport on 21/2/2020 by post(hard copy),i enclosed both our passports and our documents on one A4 envelop including one cheque for both our applications. I also enclosed a registered/paid for A4 envelop addressed to me, with a note requesting our documents to be send back as recorded.

I received a letter by post on 2.3.2020 asking for my daughters passport pictures minus her glasses. I send them pictures on 6.3.20.

This morning 13.3.20, i just received my daughters documents back via special delivery ie nationalisation certificate and her passport plus a small note saying her British passport is in process.

My question is, my documents have not been send back.
And my application they didn't request any further documents, so am assuming there is nothing else they required from me.

I am just concerned could they have send my documents back and they are stuck somewhere? Or is this normal?

Documents are sent separately via normal post. I think when you apply online you can pay extra so they send your docs back via secure post but by default they send them visa normal post