Oookay... this is a bit of a loaded question, so my answer might be long... but bear with me ;)
First of all, I've been dancing off-and-on for about five years, and my basic invert SUCKS. I know that it sucks because my knees barely clear my hands, and it's still very tiring and difficult for me to do. I am improving, but... still, it sucks. To be fair, I only managed it recently, within the last six months or so.
So, your progress is your own. You cannot compare your journey to other people's, because you will have different challenges, and they will have different challenges. I see this often at the climbing gym, too- I could do two or three 5.7 routes before I could do the easy-peasy 5.6 route that we put children on. It took me ages to get it.
Next, you are going to have to seriously evaluate how you are judging yourself. My writing, for example, is something I CONSTANTLY judge very harshly, and I am always coming up short of my "goal." It's terrible, and I catch myself doing it all the time. This is an artists' plight, but you'll see it with almost everything these days.
Take a moment to acknowledge that you can do SOME spins, where three months ago, you could do none. Take the time to look at the progress that you've made, and allow yourself the congratulations you deserve. Three months is not a long time, if you think about it, and for you to be working on pikes and butterflies, is a big accomplishment.
I cannot stress strongly enough, though, that you will always find someone better than you, and if you keep comparing yourself to anyone else (even classmates- ANYONE), you'll judge yourself worse than you judge them.
You are doing awesome. If you feel good about YOUR workout, and YOUR dancing, that is all that needs to happen. Your journey is yours alone.
Besides, what if all those other people keep looking at you and think "Oh man, I LOVE the way she does that spin! I wish I looked like that!" 😉
