19 week old kitten , lumps?

ok dont ask me to go to the vets as i have tried ringing all over and most are shut for christmas , apart from the emgancey ones , i have phoned them but they will not class this as an emgancey.
so. i was stroking my kitten in bed last night and i felt a pea sized lump underneath her nipple . its like a small hard mass , to try and be more detailed , when a cat is pregnant there milk ducts get a mass yea? well its simialler to that but hard and pea sized. so then i check her other ones and found 2 others the same . her nipples have always been a bit bigger then her sisters and more noticalbe , but i was told that in black cats they was. she has not been in heat as far as i know she has never been outside , btw im in london and no vet will spay untill 6 months , were still in the victorain times lol. i had my 8 month male cat spayed 2 1/2 weeks ago but has been seprated for the last 3 weeks. im going out my mind with worry she is ok in her self very loverbal eating drinking using her litter tray, but any suggestions what it could be , my vet dosnt open again untill 27th december. would it be ok till then? or should i just pull a fuss at the vets and get her seen to?

So long as she is acting OK - eating, drinking, playing, sleeping, potty'ing - all normally, I think it is safe to wait to go to see the vet. If any of that changes, or if the lumps become open, begin to weep or ooze, or if you notice any change in size or if they seem to be painful to her, then pester your vet to see her or take her in to the Vet ER.

thanx for that , i just came of the phone to the vets again, they have told me to bring her in on the 27th they said if anything changes then bring her straight in . i dont think they could open up as its right underneath the skin you cant see the lump only feel it . but i will be keeping a check to make sure they get no bigger. its just worrying me what it could be , i checked her sister just incase i was over reacting , but she seems to be fine. grr what they put us through , especially this time of year lol