Typing from my phone, sorry if I miss anything

I'm 25. I work at a clothing store in a mall near Samut Prakan. Been with my boyfriend almost three years and we're planning to get married at the end of this year — he proposed. Small wedding, close family at my parents' place back in Loei. But his money habits are driving me so stressed, like really stressed.

Short version: he spends so fast. Like buying expensive game consoles at like 2 a.m. And then the next day he'll ask friends to split some cost and tell me to cover the rest. Reading that makes my head hurt. Why is it like this? I'm so confused lolol

We agreed to split wedding costs half-and-half, but once we started booking stuff the prices kept going up and he never tells me in advance. He usually says “we'll pay later” or “I'll figure out how to pay” then disappears to play on his phone and goes up to his room for like 45 minutes. Sometimes he brings me a tiny pink keychain and says he’s excited about a new thing. Okay I get it, but if everything keeps happening like this our plans get shaky. I even found a receipt for a gym membership in his wallet — I had no idea he had that monthly fee. He never told me. It feels like he has his money and there’s the money I have to handle. It's not equal.

I'm someone who likes a simple life — organizing stuff at the store, serving customers, paying rent month to month. I have about 10,000 baht saved for emergencies, not a lot. Thinking that I might have to manage all the finances scares me. If something happens, who would be responsible? It makes me feel like I'm the only teammate on the team, you know?

He likes stashing cash in a piggy bank secretly. I never demanded to see his account, but when I get serious and want to talk about the budget he says “we'll talk later” and runs off to play on his phone. I'm not a suspicious person, but when you plan a life together you gotta talk often, right? Or am I overthinking?

There are also problems with household responsibilities. He says he'll help but when it comes time he forgets or is lazy. I end up making small decisions because if I don't do them things get stuck. And when money comes up he dodges the issue. That's making me feel like we're not on the same team. It's weird.

We had one open talk and he said he's afraid I won't understand that he wants to enjoy life, doesn't want to always be thrifty. I get that, but his idea of happiness clashes a lot with my plan. I told him straight that I don't want to be the one organizing the wedding and carrying the costs alone, but he doesn't really change his spending habits and won't discuss details. It's exhausting.

Now I'm hesitating about the wedding. I want things to go well. Should I postpone? Cancel? Get more serious talks first? Or accept that everyone has different money styles? Or am I just overly stressed... I'm confused.

Friends on Pantip who've dealt with this, can you share ways to talk so he doesn't feel attacked? Should we set financial rules before marriage? How should we split accounts? Any polite ways to get him to open up about a combined budget?

Totally new to posting this, please give me advice T_T