You were right on the first part in that only under VERY rare and special circumstances might a protestant be allowed to receive holy communion with the eucharist but I’m sorry, you are very wrong about Catholics being allowed to receive communion in a protestant service. It has been said before, a Catholic can differentiate the real presence in the Catholic Church to the mockery of Christ fake presence in protestant churches. To partake in this, regardless of reasoning, would be slapping Christ in the face. And that’s something I don’t think any christian, Catholic OR Protestant should want to do. I would encourage you to read up on the Catholic Church by yourself. As opposed to listening to your pastor speak about it as this is always hit and miss. Some pastors have presupposed ideas about the Church that they are all too eager to spread amongst their congregations. It just seems you are trying to speak on the Church from a position of knowledge when clearly there is none (and I don’t mean that in a confrontational way). Catholics can often be ignorant of how protestant services work but the reverse to this is exponentially true. Seek Christ with all your heart and prayerfully you will find your way home to His Church, the Catholic Church. God Bless.