Things take time to change, it’s not going to happen instantly.

If you have been trying to manifest her for a really long time, that usually means that there is a flaw in how you are applying LOA teachings. You need to ignore current reality and put your focus on what it feels like to have her already. As long as you are in the feeling of wanting her and noticing how current reality is still the same, nothing will change.

Selfloveiskey & Fizzy are both correct.

You have to believe and live in the end result. I also had to quit telling my friends. It was messing with my beliefs.

What has really helped me is listening to Veronica's and Agnes Vivarelli

My ex(Matt)ended the realionship in January but still wanted to be friends. About 2months later he reached out. Said he got cheated on.

I am not with him yet but I know I am(living in the end). I never refer to him as an "ex" I always say to myself I am in a loving renewed realuonship with Matt.

I gave up any old habits or items that no longer served me. I also brought Veronica's books on Amazon & purchases her email packages.

I started a gratitude journal. Even if I don't write in it, i always tell the Unversive what I am thankful for.

Hopefully that helps out.

If you are "hopeless" and "missing" her then you're not in the right energy to manifest her back.
I would recommend that you stop any techniques or processes for now.  Just focus on self-love meditations to get back to a healthy set point.  Then you can start other processes (visualization, imagination, RI/RS, etc).  You've got to be ok with her first BEFORE you can manifest her.