I feel like I'm the only one that can notice change in my body?

I've been working out for about 3 weeks now every day doing about 15min of exercise. When I look at myself in the mirror I can see slight changes in tone and my abdomin feels a lot more firmer. But I don't think it's enough for anyone to notice?
https://tinypic.com/r/xg0ikn/8

First two pictures are from the day I started and the last two are from a few minutes ago, I know it's not a great photo and bad lighting but it's all I had.

Can you notice anything.

Plus how to I work out my lower abdomin I've tried the reverse sit up but all I get is my legs clicking like crazy and feels like the work out is mainly situated in my thighs, I only feel a very slight bit of work on my lower abdomin
I feel like I'm the only one that can notice change in my body?
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