You have so little data that it is hard to know. Assuming that your evening number before the shot will be higher than 344, you could shoot the 1.5 and be very safe. I think you would be safe with the 2 units also, but it is not as sure a deal. It could be that the food and the insulin have just started to work and you may be seeing lower numbers.
It will be much easier for you (and us) to decide on a dose when you have more numbers Tomorrow get your preshot number and try to get some mid cycle numbers - like 4, 5, or 6 hours after the morning shot. That will help us see how the insulin is working.
All: I helped Rose with her spreadsheet and she wanted an idea of what numbers to look for. Rose, here is a VERY general guide, knowing that every cat is different.
Treated but not regulated [often above 300 (16.7) and rarely near 100 (5.6), poor clinical signs]
Regulated [generally below 300 (16.7) with glucose nadir near 100 (5.6), good clinical signs, no hypoglycemia]
Well regulated [generally below 200-250 (11.1-13.9) and often near 100 (5.6), no hypoglycemia]
Tightly regulated [generally below 150 (8.3) and usually in the 60-120 (3.3-6.7) range, no hypoglycemia, still receiving insulin]
Normalized [60-120 (3.3-6.7) except perhaps directly after meals -- usually not receiving insulin]