Shoes won't necessarily hold you back but it's always handy to have an advantage me personally when I changed from jokers I was amazed at actually how bad my foot work was where I previously thought it was ok, with a more aggressive shoe I could get my toe on and actually feel a lot more and realised I wasn't as accurate with my feet as I could have been.
Best people to ask really would be your missus and mates as they see you climb we can only speculate (and make jibes as above) about how best to help. I personally think it's not your shoes but technique and the fact you're climbing at a fair grade which requires better application of foot placement however as you said, your finding the issue on all routes so it's hard to assess. Yeah cleaning your shoes is all very well and good but I climb 2 / 3 times a week now I never clean my shoes and I'm starting to get holes in the toes and the edge is wearing just means I have to press harder and ensure my toes in a good place. You could resole your shoes but general consensus is it's a bit pap so the last avenue is new shoes, considering the cost of mtb kit £80 on a pair of climbing shoes is nothing so why not treat yourself.
All in my opinion of course