Where to go for bra fitting

[Lilipot15]

I know there are a couple of other bra threads active but they don't mention the best places to go.
I'm still breast feeding and have been either feeding or pregnant for 3 years now, so I have lived in stretchy comfy feeding bras.
But I am back to work soon and need a decent bra. I have put on weight and my old ones don't fit - they are all M and S.
I understand they're not the best, but where do I go in a small town, or do I travel to somewhere bigger? I'm not too far from a bravissimo but I don't think I'm a d cup or above.
I'm not confident enough to measure myself and I also need to look at styles.
BUT, presumably things are likely to change once I stop feeding, albeit only 4 times max in 24 hours, so I'm not looking to spend a fortune!

A d cup really isn't that big - do you have a measuring tape? Measure as described here just to give you a rough idea of your size. If you have more than 4" difference then Bravissimo, otherwise John Lewis are generally ok. Not M&S. They use an old fashioned fitting method where they add 4-5" to your band size, which means you end up in a bra several bands too big and several cups too small

Thanks - I'll try and locate my measuring tape and do an approximate measurement myself. Are John Lewis cheaper?
Presumably I should antipicate a change once I stop breast feeding too? Although DH informed me he thinks I look a lot smaller, not sure if that was a compliment as I did go on about them seeming too big!!