I'm a female. I got my bike on the 22nd of july 2020, I cycle quite regularly- 3-5 times a week. I really don't want to pay for gym membership because the cycling is already expensive enough- with kit, accessories, maintenance etc.
You've been riding for just over eight weeks so you will have noticed some difference but if you keep it up, you will see significant gains over the next six months.
I've been cycling 100 miles a week since March and commuting over hills for four and a half months. The ride doesn't seem any easier but my commute time has dropped by over 30% since day one for the same level of effort. The main gain has been in my speed up the hills but I still wouldn't describe myself as anywhere near quick. I've gained leg muscle, reduced my resting heart rate and I can get to the top of the biggest climb without my lungs bursting. I've now set myself a target of reducing my commute time by one minute per week and I reckon I can do it by working even harder on the hills.
As for cost, you will spend a lot on bits and bobs to start with like helmets, lights, racks, panniers etc. but that will taper off over time.
Maintenance is something you can do yourself and there has never been so much information readily available online on how to carry out any job on a bike. Go online, watch a video on how to fix any particular problem and without any prior knowledge or skills, fix the problem.
Bike mending is a hobby in itself and if you do it yourself, you will learn to understand your bike so much better and your riding will improve as a result.