I don't limit carbs. I worked with my endo years ago to figure out a healthy diet for me. Then, we figured out how much insulin I needed to cover what I was eating.
This was before CGMs were available. So, if I wanted a donut or muffin for breakfast, I would check my blood sugar first. If I was high, I might reconsider that donut, but if my sugar level was in normal range, I would guess how much insulin I needed. When, I'd eat the doughnut, wait 3 - 4 hours, and check my sugar again. If too high, I would take more insulin, and I knew the next time I was going yo eat a donut I needed to take more insulin beforehand.
These days, with CGMs, it's much easier to see how the food I eat affects my blood sugar. It is also easier to find the amount of carbs in the food I am eating. So, I now look up the carbs for the donut (pre-packaged are much easier, just look at the nutrition label!), and bolus accordingly.
Also, the timing of your insulin is important. High simple carbs, like donuts, will hit your blood sugar faster than high fiber carbs like beans. So, you need to take your insulin 15 - 20 mins before eating the donut so your insulin will be starting to work as you eat it. You might even need to take it up to 30 mins before eating the donut depending on the type of insulin and how quickly it starts yo work in your body. For the beans, 10 - 15 mins before eating is fine because they digest more slowly.
Counting carbohydrates (carbs) and insulin timing are two key factors in controlling blood sugars. I look online to find carbs in my meals, especially when eating out. CalorieKing.com is a good site to get you started.

There are several factors but I've done a lot of analysis on myself over the past 10 years. I even wore 2 CGM(S) a Dexcom G7 and a Lingo. The Dexcom G6 and Eversense. All to give me more insights. Generally speaking I can do a reasonable job. After a long fast like waking up I generally don't eat something with a lot of carbs. I may eat high protein yogurt then a few hours later I may eat a meal with more carbs like fruit or a protein bar. The same is true for my dinner low carbs unless I'm going to work out. Also be aware of cortisol I do a lot of road cycling and if I've really killed myself on the bike while I'm riding I'm eating like crazy but as soon as I've stopped my sugars jump like crazy as if I've eaten chocolate cake with syrup. Track your diet using an app and do the best you can. Some crazy variable will happen that is outside your control and you just need to let it pass. I'm generally 85 percent in range 70 - 180 but about every other week I'm just going to have a crappy day and be around 55 percent it is just the way it is for us Type 1's.

A spike in blood sugar after eating is normal, but should be kept to a minimum. This is achieved through timing the insulin with food absorption. IE: Taking your insulin 5 - 20 mins before eating (the timing will vary depending on how quickly your body responds to insulin, and what type of food you are eating).
Other things that can affect blood sugars are many (see above). The weather can even have an effect!
So, if your time in range (TIR) is good, don't worry about a few highs or lows. If your TIR is not good (generally below 70% of the day), keep track of your blood sugars for a few days, and look for patterns. If you are always high at a particular time of day, or low, your insulin may need adjusting. Discuss this with your healthcare provider.