Here is the therapy you really should spend money on, but probably won't.
my Dad was/is very controlling with money! I remember my mum hiding money from him and telling me to keep it a secret.
I think you're casting your husband in the role of your dad - not consciously, but our unconscious minds have an incredible knack for making new situations fit old stories.
You mum wasn't allowed free choice on how to spend the family money.
"Men punish women for frittering the money, I'm afraid to spend on myself."
Even when he TELLS you to spend money on yourself, you don't believe him.
You've implied that you need him standing next to you, making choices, giving you permission, maybe even taking your new stuff to the till and paying. This would, in effect, prove he's not like your dad. But would your unconscious mind believe it? Would you still be subtly waiting for the punishment?
he will say while having coffee or something let’s look for you, but then will walk straight past and into a men’s shop again.
"Look, look! He doesn't mean it. He says that, but ... there will be punishment."
He's not your dad - and well done, by the way. Most of us manage to marry another version of our fathers, so your unconscious wasn't completely stupid.
You cannot possibly expect DH to find ways to embody your father's worst habits, then perform extended rituals simulating his transformation from a controlling miser to an open and generous partner. That would be an unrealistic, practically insane thing to ask. Yet it's what you seem to desire. It's unfair to DH, no?
As time goes on I am feeling like I need to shrink myself more and more
Congratulations, you've found a way to hide like your mum did.
But you are not married to your dad. You're using inappropriate coping mechanisms: ones that kept your mother safe, but your marriage isn't hers.
Out of interest, do you have a secret personal account, or a cash stash?
Frankly, you do need therapy but - since your husband sounds like a generally well-disposed guy, perhaps you could get him to read through this thread with you and come up with solutions.
Would a defined budget be helpful, for instance? I don't think he should do the "shopping for you" performance as this won't relieve the underlying problem. But, if he perceives the nature of your issue, he may be open to making a constructive plan with you.
Good luck! Enjoy your new haircut, clothes and shoes.