I would always err on the side of BG going too high - you can always add extra insulin but you can't take it away.
However, given your doses are relatively low, I would also recommend requesting a half unit pen. These are available or most insulins. However, I am not sure if they are available for the cheaper biosimilar insulins like Trurapi. If this is the case, I would argue that you need a different insulin (e.g. NovoRapid) which can use half unit pens. Otherwise, you are potentially using more insulin than needed and the cheaper insulin is a false saving.
Ooops sorry, I veered off topic there with a bit of a rant. My apologies.