What happens for many of us is that we need a little less basal insulin in the summer compared to the winter, BUT because you are likely still in the honeymoon period, you may not see this just yet as your basal needs may be increasing as your remaining beta cells die off.
The other thing to consider is, are you a person who enjoys hot weather or do you find it uncomfortable. If the former, then you may find you need less insulin and if it stresses your body and makes you feel uncomfortable, then you may need more insulin.
As with everything diabetes related, it depends on the individual.
As regards correction factors and doing a correction when your levels are higher than you would like, it was suggested to be that I start with the approach that 1unit of insulin might drop me 3mmols, so if I was on 11mmols before my next meal, a 1unit correction could take me down to about 8mmols or 1.5units would take me down to 4.5mmols (3+1.5) to bring me down to about 6.5mmols. I would then add that calculated correction to my meal bolus, so if I was having 40g carbs and I had a meal ratio of 1:10 then I would bolus 4u for the food plus a 1.5u correction so I would dial up 5.5 units and hopefully, if that correction factor was right my levels would be about 6.5mmols when that insulin had finished working (usually about 4-5 hours later..... assuming my basal insulin dose was keeping me steady. If your basal dose is not keeping you steady then you really can't draw any useful conclusions from the result you get, so doing some basal testing is usually the starting point before you start trying to work out correction factors or adjusting meal ratios.
I am giving an example of what was suggested to me for correction factor starting at 1u drops you 3mmols. If you are very sensitive to insulin then 1u might drop you as much as 6mmols. I believe if you use a 1:10 ratio for meals then a 1:3 correction factor is usually somewhere near, but again it can vary with time of day (morning usually being when people need more) and BG levels and can change over time as everything tends to do occasionally with diabetes.
You should not calculate and inject a correction in between meals unless it is more than 4-5 hours after your previous bolus because you will still have active insulin working. So for example, if your levels spike up to 15 two hours after breakfast, DO NOT be tempted to do a correction then because the insulin that you injected for breakfast will still be working and could well bring you down into range by lunchtime and if you were to add extra insulin on top, that could cause you to hypo. However if by lunchtime you are still sitting at 11 or 12mmols then you would add a correction provided that it is 4-5 hours since your last injection.
Once you get more experienced, this advice becomes more flexible and I certainly correct between meals sometimes but until you learn how your body responds then you are best following the guidelines to only correct just before your next meal and add it to your meal bolus.
Have you been offered a DAFNE (Dose Adjustment For Normal Eating) course? If not, then ask about this as it will give you the opportunity to ask lots of questions like this and learn when to adjust your basal doses etc. Mine was a week long course but some places do it as 1 day a week over several weeks. There are usually only 6-8 people on each course, sometimes less, and there is a DSN and diabetes specialist dietician who scope take the course, so you have the opportunity for lots of questions and can discuss any problems the next morning, when you go through your previous day's results and see what you can learn from them. You also learn how to problem solve for other people as usually people have different issues with their diabetes management. That stands you in good stead for when your diabetes changes and you start experiencing different problems. You also get to spend lots of time with other Type 1s and that in itself can be one of the highlights of the course.
