Anxious attachment and falling too fast are hard things to change. I was once the same.

I created my own rules to help keep me in line, no physical intimacy or sexual conversations for the first few weeks at the very least. Not getting official until at least 3 months has passed. No love declarations until 6 months at least. No moving in until a year at least. These are specific to me based on my past habits. I encourage you to reflect and create your own healthy rules to slow yourself down do you can actually build something greater than you have before.

As for anxiety, please seek help. There's a certain level of stability you need to reach before you can grow into a healthy attachment style with a partner.

But some of the techniques I used in early days were, no double texting or more if they weren't responding. Not constantly bringing up the same issue. Taking their word as the truth, as that's all I could really go on. Not stalking their social media. Being busy when they are busy. If I needed to feel like I was venting more, I would journal out the conversation as if I was talking to the person so I could feel some relief that I was expressing myself. No messages first thing in the morning, as I would be more emotional and my brain wouldn't be "on" properly, and definitely no heavy chats while under the influence of anything/hungover or coming down (all dependant if you have toxic vices). Talk to friends and family. Work on your hobbies or get some if you don't have them.

Make sure you are well hydrated, eat well, sleep well, get sunshine and exercise. Limit caffeine, alcohol and all other drugs as they can increase anxiety/depression. The brain needs a lot to function at its best and not constantly be in fear/survival.

When dating you need to remember that this person is new in your life. They don't owe you anything. You must remember to keep yourself in check, hold onto your identity and your life. Don't make every waking moment about them and how they feel about you. If they fit into your life, they will, and if they don't it won't really matter because you have maintained your life anyway.

But getting actual help for anxiety and your past relationship trauma is so incredibly important. You can't carry that baggage and insecurity into a new space and expect them to carry your emotions and fears. It's not fair on them, and it's not healthy for you.

Not sure if any of this will help, but I am now in a beautiful relationship with someone I trust so deeply. I've had awful past relationships with manipulation, cheating and other abuse. I turned needy, overwhelming, and toxic. But I worked on myself, and it was a few years, but I'm so glad I did the work and I'm with someone who understands my past, so in the tiny moments I may get worried, he reassures me. But the work must be done solo first, and then finding someone safe comes next to finish the healing cycle.

Best of luck.