There are a few things to tackle here.
In the first instance, I don't know your full diabetes diagnosis history but reading between the lines I'm going to assume you are a 'classic' T1 diagnosed in June of this year.
If that's the case, that would likely mean that at the time of your diagnosis, your body would have been severely dehydrated and you would have lost a lot of muscle and fat through diabetic ketoacedosis. When I was diagnosed, I looked like a concentration camp inmate.
Once you went onto insulin, the DKA stopped. Your body stopped eating itself to death, and it stopped flushing pints of water out through your kidneys. It started rebuilding muscles and it started putting fat in the places you need it to protect your organs and your exterior. All of this will cause weight gain and it can be quite dramatic. I was diagnosed at the age of 14, probably around 5'8'' and weighed around 6 stone - I put on probably a good stone after diagnosis.
The important thing to realise then is that while you might have gained weight, this doesn't necessarily mean you are 'fat', or even getting fat. While a T1 diagnosis happens pretty rapidly, you probably get a good couple of months of so of being fairly skeletal to the point that your body rationalises it as normal. I would imagine it's very, very common for newly dxed people to suffer massive body dismorphia because they're so used to interpreting 'underweight' as normal. You already say you're 'normal' with your extra 10lbs, so I would say you shouldn't be trying to lose this weight at all. Otherwise you're just trying to put your body back into the same dreadful state it was at diagnosis. You don't want to do that.
However, if left unchecked, you can of course put on more weight than you really need to. Here's the dirty little secret - exercise isn't the biggest influencer in whether you put on weight. Exercise keeps you fit. Exercise boosts your metabolism. Exercise reduces your insulin resistance. But what really influences your weight is your diet.
Here's the other dirty little secret - fat doesn't make you fat. Dietary fat breaks down into acids which are actually very hard to convert back to adipose tissue. Carbohydrates, however, break down into glucose, which is the precursor to adipose tissue. Excess blood glucose is converted to fat. So if you are looking to lose weight (or even just maintain it), generally it makes sense to reduce your intake of blood sugar raising foods. That's more than sugar. It's noodles. It's pasta. It's fruit. It's bread. It's cereal. It's juice. If you are eating fewer blood sugar raising foods, you'll need to reduce your insulin accordingly.
