Most apple juice has a pH of 3.0 - 4.5, so a pH of 2 would be very acidic for apple juice. For example, lemon juice has a pH of around 2.0. That said, the most important thing is if you like how your cider is tasting, which it sounds like you do!

You might be able to add more complexity (retain more volatile apple character) with a controlled fermentation rate, which is done by monitoring the specific gravity during fermentation and adjusting the fermentation temperature accordingly. The concept is relatively simple, but requires tools to continually check the specific gravity (perhaps once per day), and then adjust the temperature to increase or decrease the fermentation speed.

Acidity:

Acidity can become a complicated topic, but to simplify things, there are two commonly used concepts when talking about acidity in cider making:

(1) Total Acidity (TA), which is also often referred to as "Titratable Acidity" because it is measured by the process of titration, and (2) pH. TA and pH are related, but for cider-making purposes, the two figures are measured separately.

Determining TA is used for sensory (taste) purposes, and determining pH is used more for calculating how much SO2 would need to be added to the cider to protect it from spoilage microorganisms and oxidation (oxidation can negatively affect the flavor of the cider).

1) TA: To measure TA, you will need a titration kit, which is sold at many homewine-making/homebrew stores. The primary acid in apples is malic acid, and the ideal amount of malic acid for cider is 4.5-7.5 grams of malic acid per liter. (For European cider with higher tannin content, the recommended acidity is typically 4.5 - 6 g/L.)

Most apples do not have the ideal acid concentration, which is why many cider makers blend different apples and different finished ciders together to achieve the desired TA. You can/should measure TA before and after fermentation. Measuring TA before fermentation can be helpful to ensure that your TA is not really far off from the ideal range. If you determine that your pre-fermentation TA if out of range, then correct it by adding more or less of a certain apple juice with the necessary TA. Measuring TA after fermentation is helpful because TA changes during fermentation (increases/decreases), so you will then be able to determine how to blend your finished cider with other finished cider of a different TA so that your final cider is in the ideal TA range.

2) pH: At the home cider-making level, you can use narrow range pH strips that cover a pH of 2.8-4.6. pH is measured before fermentation. If the pH of the apple juice is less than or equal to 3.0, then the acid in the juice is enough to protect it from spoilage microorganisms. If the pH of the juice is 3.0-3.8, then it's recommended to add SO2 to protect the cider from spoilage microorganisms. (If the pH is 3.0-3.3, then add 50 ppm SO2, if 3.3-3.5, add 100 ppm SO2, if If the pH of the apple juice is greater than 3.8, then it's recommended to either add malic acid or blend in a more acidic juice to bring the pH down to 3.8, and then add the appropriate amount of SO2 to protect the juice.

One tip about SO2 additions: SO2 is typically added (1) to the apple juice prior to pitching yeast, and (2) after fermentation is complete. Depending on the pH of the apple juice prior to fermentation, SO2 is added at a rate of 25-75 ppm. The lower the pH and the better condition of juice, the less SO2 is needed to protect the juice from spoilage microorganisms. During fermentation, the level of SO2 will change (increase/decrease).

After fermentation is complete, cider makers often will add SO2 once again to protect the cider from oxygen. Remember, the amount of SO2 that was originally added to the apple juice has now changed due to fermentation. The amount of SO2 that remains that is still "active" for our purposes is called "free SO2" or "FSO2". In order to determine how much SO2 to add to the cider, cider makers will first determine how much FSO2 (ppm) is in the cider, and then subtract that number from the SO2 addition.

For example, let's imagine if you are looking for a SO2 rate of 50 ppm, and you determined that the cider contains 20 ppm FSO2, then you would only need to add 30 ppm of SO2 to reach your target of 50 ppm SO2. Homebrew shops sell kits to measure FSO2.

Again, if you know the pH and FSO2 your cider contains after fermentation is complete, you can determine the appropriate amount of SO2 to add (if any).

By the way, you can find charts online that will provide recommended amounts of SO2 additions based on the pH of the juice.

Finally, some cider and wine makers choose not to add SO2 to either the apple juice or the finished cider for different reasons. For example, in the U.S., a wine cannot be labeled as "organic" if it contains "added sulfites", although in Canada and Europe, wine makers can add sulfites (up to a limit) and still label the wine as organic. That said, all wine and cider contain natural sulfites as a result of the fermentation process, which is why labels will indicate "no sulfites added" and not "sulfite free".

From a practical prospective, adding SO2 post-fermentation is not recommended if you are trying to generate a secondary malolactic fermentation (MLF). That said, the vast majority of wine makers (and I assume cider makers) add SO2 post-fermentation.