Hi
@Ana W and welcome to the forums.
That does sound very scary and a shock for you.
I'm surprised they haven't sent you home with a libre, though I would expect that they have at least given you a glucometer? (Unfortunately libres aren't accurate in all circumstances, so it's a good idea to have a glucometer to double check when your blood sugar is doing unusual things - high or low.)
The good news is that DKAs are usually pretty rare, they are most common at diagnosis when you don't know that you need insulin. (I've been T1 for 54 years and never had one, as I was diagnosed very early.)
The problem with insulin is that people need widely differing amounts (one person can need 10 units a day while another needs over a 100) , so there is no fixed amount of insulin for carbs. Generally they try to start people on a low dose and gradually increase it till the amount is right for that person. (And it doesn't help that insulin needs can change with time, particularly for new diabetics.)
It sounds like you are on a basal/bolus regime.
The long acting basal insulin (lantus for you) is meant to keep your levels steady when you don't eat eg through the night. It's often referred to as background insulin for that reason. The novorapid is meant to both cover the food you eat for meals and (when necessary) act as a correction dose to bring your blood sugar down when it is high. In the long run you'll probably learn to count carbs and then you'll be calculating your meal time dose on the basis of so much for the carbs plus a correction dose (which can be negative if your bg is too low). (Bg = blood glucose).
Have they given you a phone number or an email address to contact the clinic?
Hopefully now you've experienced your first hypo (hypoglycemia, low bood sugar) you'll recognise the symptoms in future? It's actually not uncommon for non diabetics to have blood sugar that goes that low, but the problem for diabetics that injecting insulin means that you can go much lower. So it's a good idea to always have emergency carbohydrate with you (jelly babies in your case but different people use different things) so that if you go low you can easily raise your blood sugar. (If you go lower you can start to get confused and it's no fun trying to search out carbs when you can't think straight.)
If you keep good records of the amount you eat and your blood sugars before and after meals your team should be able to adjust your insulin doses and ratios for you. Yes, the idea of a basal/bolus regime is you only take the bolus (novorapid for you) when you eat carbs, but I suspect that at this stage your team will want you to eat normally in order to find out how much insulin you need. (I stress that this is not medical advice, we're not allowed to give you medical advice.) In theory you can adjust your insulin to eat a high or low carb diet - if it's very low carb you may have to start allowing insulin for protein and fat as well as for carbs. But at this stage we have no idea whether you are still producing small amounts if your own insulin so that is really hard to say.
If I was in your position I'd probably try to concentrate on
1) good record keeping for my team to calculate my insulin needs. (Some kitchen scales might help here, a typical slice of bread can be between 10 and 40g of carbs, depending on size. Luckily lots of supermarket foods have carb counts on them)
2) avoiding and treating hypos.
And if you've got an email address or phone number, keep asking your team questions. In particular, the 4 you've asked here are ones they should answer for you. They may be busy but as a new insulin user they need to help you.
Sorry for the (too) long essay, good luck. Things will get easier with time.