Personally I would go for the whole patch (but as Sunnydays says why not experiment - and just cut a corner off a full patch for a while and see how you go) as it's still not a very high dose and especially if your flushes are creeping back.
When I stopped HRT a few years back (gosh it was 5 years ago!!) for 3 months, and then went back on it as symptoms returned, the doc suggested 25 mcg to start with (ie half patch). This worked for a while and I thought great! However flushes crept back so went back up to the previous dose of 50 mcg which I have been on ( almost) ever since. 12.5 mcg ( ie 1/4 patch) is such a negligible amount to increase by - unless you are extremely sensitive.
Also as you are in cyclical HRT you are not taking the synthetic progestogen all the time. It is the women on Evorel conti all the time that sometimes find anxiety is increased and think it's due to too much oestrogen - which is extremely unlikely - it is the synthetic progestogen which can cause problems. If it's suiting you then great! let's hope that continues

Hurdity x