Good for you, stick to your primes.
0.Use one lens and stick a modifier to it.
There are modifiers that change the lens into something wider or narrower. There is a reason this is recommendation number 0. These modifiers are almost always, no not almost but always, crap. But this is an option if you don’t mind the loss of quality. You can probably get as “good” results just by sticking concave and convex lenses to your primes. I would rather just have a zoom and that’s saying much.
1.Zoom with your feet.
It is cliché, but for a reason. Often just moving around resolves the issue and more importantly, gives you time to think about the picture and see other angles and view or compositions that you hadn't considered.
2.Alternate between the lenses.
One time period like a day, or a week take one, the next the other, or this lens for this specific project, that lens for this other one. That will force you to be more creative. If you only have the 15 that day and want a 35 type shot, you will find a way to do it, and do it better than if you had the 35.
3.Stick with one.
Chose either lens and use it till you master it. Get to know it, so you can transcend the camera and lens. Also, each lens is unique and behaves differently, the more you know yours the most you can get from it. From general to specific the individuality goes something like: Primes, 50mm, this 50mm lens design family, this 50mm model, this generation, this batch, this particular lens. If you know the lens you will know that in this situation, with this camera, at f8, ev11, you stop down 1/3 and take it at that angle.
4.Chose the 50mm lens and use it till you master it.
As you probably know H.C. Bresson shot all his life with a 50mm. while it is unusual and most street shooters use something closer to 35, the 50’s are generally the best in lens Quality. 15, or 23 eq seems quite wide to me and is probably not as well built optically and slower. The 35mm in FF were also very good and you are benefiting of 100 years of lens designs I would use the 15 more for indoor situations were you need legroom. However it is a personal preference, if you prefer a very wide angle of view then stick to it.
5.Get a 3d lens.
Yes it would make your problem worse, but you are missing out on a 70 or 85 lens. Yes, even for street I would recommend a moderate telephoto. It gives you a fresher and different perspective than wider lenses; Get a 50 mm, it will be eq to a 75 an ideal “portrait” lens length. Also remember what I said about lens design and inheriting from past experience. In most systems the 50 is the best value of the bunch quality build, lens design and speed for an unmatched price point.
6.Laugh at Zooms.
With this trinity of 15, 35, 50 you can confidently laugh at folks telling you their zooms are as good as primes and outshoot them with your primes on an APS-C camera against their FF flagship body with the professional zoom.
7.When you master your lenses, you can decide whether to bring one or all.
If you only shoot streets I would probably recommend one, the best use of lenses is a specialized one, or even get a good quality non interchangeable lens camera. Look into the Sigma foveon sensor for instance, super quirky but super quality too. Else you can go the rangefinder route with mirror less. If you do more street plus general photography bring what you can and maybe a tilt shift if you do buildings, a macro for details and maybe a telephoto.
