めちゃくちゃ（会いたい）って英語でなんて言うの？

These are all nice expressions expressing your need to see a friend, relative or loved one.
Instead of using the word 'really' several times these are other examples of how you can express your excitement.
"I'm so excited to see you, I can't sleep thinking about it" shows that you are constantly thinking about that person, even when you're trying to sleep.

I'm dying to see you is an example of hyperbole, we are aware you aren't literally going to die but it expresses a strong want and desire.

I need to see you expresses urgency too but can have an overly serious tone for some circumstances.

I can't wait to see you, again the urgency is there but with a more desirable and patient connotation.

Hi Ayane :-) I hope this helps! :-)
A) I'm dying to meet you. - eager to / excited to meet someone

B) I would love to meet you sometime soon. - You would love to meet someone in the near future

dying to' means is to be eager to do or to have it

Repeating 'really' will convey that you are excited to the the person
Note, however, that there are shorter ways of conveying that message
_
A: Are you coming over tonight?
B: Yes
A: I really really really want to see you

A: My flight lands at one
B: I am dying to see you.

These expressions all convey a strong desire to see a person. We commonly use phrases like 'I miss you' in English especially when talking with a loved one. If you want something more casual for a friend then something like 'It has been too long!' is good.

1. This means that words cannot express your deep feelings.
2. This means that you cannot tolerate being separated from your friend.
3. This conditional sentence uses hyperbole or exaggerated speech to express your deep feelings.

ASAP = as soon as possible
Need = require (something) because it is essential or very important.

When telling someone that you would like to see them really really bad, these above will express that.

1. I'm dying to see you!
   This is an informal expression that means that you need to see the person so much that you feel that you are going to die.

   2. I desperately need to see you.
      The word "desperately" means used to emphasize the extreme degree of something. Therefore, if you desperately need to see someone it means that you critically or seriously need to see them.

When we are desperate to...Eat drink sleep...or meet again "Desperate" implies a huge need! Indeed it is almost "a life-saver":-))

"I cannot forget our last meeting...and I am desperate to see you again..."

When you are desperate to get together with someone, you can express this need by saying:

I really want to see you.
I have to see you.
I need to see you.

A romantic way of saying you want to see him/her.

The first phrase is a good way of expressing that you require seeing the person or it is very important to you.

"I want to see you urgently" Urgently means you need to see the person immediately because it is very important and that seeing them should come before everything else.

If you would like to express that you really want to see somebody, without repeating the word "really", you can say:
"I can't bare being apart from you."
"I'm dying to see you you."