Whether it's normal or not is up to you to decide - 'normal' is so subjective anyway, there's no definitive answer. What works for one person might not work for another.
But here's my take on it - if you're finding that your desires are interfering with your ordinary day-to-day functioning, like you're unable to focus on tasks or you're getting upset or angry because you're not diapered; then perhaps you might consider speaking to someone about it? When something starts to impair your everyday ability to lead a 'normal' life, then it's a problem, and you might find counselling or therapy useful to put things into perspective or to give you more appropriate coping mechanisms?
To give an example to help you understand what I mean - if someone went to a forum about beer and said "Hey guys, is it OK that I drink a beer or two after a long week to help me unwind and relax", the likely answer would be 'sure, drinking in moderation is fine'.
But imagine they said something like "Hey guys, if I don't have a drink for a few days, I can't concentrate at work because I'm thinking about it constantly, and I get angry and irritable, is that a problem?" - then I think it's clear that the person probably has alcoholism to some degree, and should probably seek help.
Now of course, it's not exactly the same situation, because I've never heard of anyone overdosing on diapers or ruining their liver because they peed their pants too much! But what I'm saying is that if something is interfering with your day-to-day life, if it's making you unhappy or if it's worrying you, then perhaps speaking to a professional is an option you might want to consider?
I personally had a good experience speaking with a therapist about my own ABDL desires, and she didn't discourage me or try to persuade me to quit or anything like that - she just helped me to get perspective on my activities and to see it as a positive element of my life.
Obviously it's not for everyone, but it's something I'd strongly suggest you consider, if it's an option that is available to you.