Regret

I've been in an on & off relationship the past few years. First real relationship. Over the past few months I started feeling less in love with her. I knew i loved her, but the spark seemed to be fading. When I was with her it was fine. I was very happy etc, knew we was right for each other. When we were apart though I kinda felt the opposite. I knew we were a good match, but at the same time something in the back of my head was asking questions.

Are we meant to be together? Is she really the girl I wanna spend my life with?

I've been in a dark place the past few weeks, and it got to the point where I barely saw her for weeks. I wanted too, but had no energy too. After a petty argument I was honest and told her I wasn't sure if it was working. I loved her, and wanted her to be happy. If i wasn't that guy, it was better for her to be without me etc.

It wasn't until we decided to break up that all my feelings came back. I've started feeling really alone, regret the decision. Miss all the things I did love about her. We said at the time we would avoid trying to make contact with each other, make it less messy that it could of been. I've failed at this badly and find myself texting her everyday asking if we've done the right thing. She's told me she's hurting too, but still thinks we should stick to it this time.

As mentioned previously, it's my first long term relationship. It is the normal to get these feelings when you first break up with someone? I'd be grateful for any advice, as I'm struggling at the moment.

Well I can't offer any advice about relationships (never had one) but if you have been in a bad place recently, have you explained to her about it? Maybe you can at least have a chance to be open about what you have been through.

Yes, it's completely normal in most cases. While the pain is still fresh, you will recall the good times and the happiness and miss it.
As time passes and the grief begins to fade, you will start to recall the discontent as well.
Did you make the right decision? You won't likely have full clarity on that until you finish grieving.
She seems to think it was the right decision for the two of you, so I'm not sure it matters at this point - unless she changes her mind of course.
I'm sorry that it didn't work out for you though. The pain from a break up can be a heavy burden.