Multilingual Children

BACKGROUND: We live in Chicago. I am a native Spanish Speaker brought up bilingual in the US, have lived and worked in Spain and Germany, where I met my husband.
When we lived in Germany, we used to speak German, but after over a decade in the US the gap between my German and my husband’s English has widened and we shifted to speaking to each other in English. But when our baby was born we decided to speak in German to each other in the presence of our baby. When we are alone, we revert to English.
We have one 20 month old boy.
We use OPOL.
When I’m alone with the baby, it’s simple, I only speak Spanish.
When the three of us are together, I speak Spanish to the baby and my husband speaks German to him.
The baby understands most of what we each speak with him.
QUESTION: While I have decided to support my husband’s language by speaking to him in German in front of our baby, I continue to address my baby in Spanish and to address my husband in German in his presence. I wonder if I should switch from only speaking to my baby in Spanish to speaking to him in German when my husband is present.
I had a similar situation yesterday when I met a German mom with her child for a playdate at the pool. Should I continue addressing my boy in Spanish or is this a time when I should be speaking to my child in my average German?