when is it appropriate to buy maternity clothing?

hi all!! I’m 21f and I’ll be 5 weeks on Monday :) for context, I’m 5 feet tall and I’ve been SO extremely bloated that I can’t fit in my own clothing. My husband is 5’9, and I’ve been wearing his clothing for almost 2 weeks (I feel like Adam Sandler) at work or anywhere else. The problem is that I’ve had so much bloating but my chest and stomach are noticeably bigger which are throwing me off but I can barely fit in HIS clothing now. My MIL works with me (we all work in a warehouse) and she told me I should just bite the bullet and buy maternity clothing now so I can be more comfortable. I still am having huge imposter syndrome with all of this, and I wanted to ask if it would be inappropriate if I went and bought some maternity jeans and just some bigger shirts.