That is correct, you cannot fulfill your Sunday Obligation in an Orthodox Church except under very specific circumstances for which you would not qualify, as a member of the Latin Church living in an area with Latin parishes, and perhaps other Byzantinc Catholic parishes as well.
“non-Catholic ministers in whose Churches these sacraments are valid” are the Orthodox ministers.
That is the Catholic side. On the Orthodox side in the US, except perhaps in Alaska, it would be difficult to find an Orthodox priest willing to offer sacraments to a Catholic.
It does not sound like you are under the direction of a spiritual father so that would be the place to turn. If your parish priest cannot help you then contact the diocese/chancery and let them know you need a qualified spiritual director who understands the Eastern Catholic Churches.
From your description you have no experience living your faith within a Coptic parish, Orthodox or Catholic. It would not be possible, as I think you have gathered, to change to a church
sui juris in which you’ve not actively lived. You might find the interview with Fr Maximos’s,
“Who are Eastern Catholics?” , helpful for his consideration about how we are members of the Church. Even though Fr Maximos is a Byzantine Catholic the initial minutes of this interview address what churches are and why we belong to them. With the help of a qualified spiritual father hopefully you can find what you are called to at this time in the Church.
Great Lent begins tomorrow evening for us. This coming week is a very important one and has additional liturgies such as Compline and Canon. This is evening prayer with Great Canon and no Holy Eucharist is involved. It would be a nice to go to an Eastern Catholic or Orthodox church for these.
Throughout Great Lent on Wednesdays and Fridays is the Liturgy of the Presanctified Gifts in Orthodox and EC Churches. You could attend these at an Orthodox church without receiving Eucharist or look for another Byzantine Catholic Church to join in celebrating these liturgies and taking the Eucharist.