Can MEPs accept me if I had a suicide attempt when I was 13?

Don't lie about anything - no matter what a recruiter says. Things always have a way of catching up. It's better to be up front and honest ultimately. If they find out something later, especially if you have to get a security clearance and it comes up in the background investigation, it won't be useful.

No one on here can tell you the likelihood of what could or couldn't happen. Ultimately, the question of a waiver are for your recruiter if you needed one. My opinion - be honest. If you get denied, it's better that it happened up front than it coming back to bite you in the ass years down the road.

Mental health waivers are very closely scrutinized now more than ever. This exact scenario is why military kids are considered to be at a disadvantage for military service if they've ever received treatment for mental health while in the military health care system. All their records are automatically available to the MEPS. Going forward with a mental health record you are automatically going to need a waiver, and the Air Force is very tight fisted with the number of waivers they grant a year. Of course if you're a military dependent who was treated in Tricare you don't have a say in it anyway.

What should you do? Well nobody here can answer that. But I do know that not all my medical records made it into my MEPS file and I loved every minute of my career. That's not an endorsement for bad behavior, just a fact the military isn't filled with Biy Scouts

It has been a while, but attempted suicide was disqualifying. As stated in another answer, don't lie about it. It may come back to haunt you and can get your recruiter in trouble.