It’s hard to answer that without more detail. What we can say for sure is that it’s not unusual to have collected no scopes since January. It is, after all, only March.
It’s good to receive an ‘A’ grade when you are attacking Titans, but the key determinant of the likelihood of receiving ascension materials is your loot tier. Getting an ‘A’ grade against 6* Titans (loot tier VIII) will produce considerably worse loot, over the long term, than getting a ‘C’ grade against 10* Titans (loot tier X).
How rewarding your raid chests are will similarly be directly affected by their tier. If you’re opening chests in the silver tier then one would expect them to produce fewer scopes over the long term than chests in the diamond tier (although with such small probability events, it’s quite possible for silver tier to outperform diamond in the short term).
And then there are events and quests. Are you completing them all? If so then you’re maximising your ascension material returns from them - you can’t do any better than that, unless you have the skills and resources to attempt to place in an event.