In-law Problems

So my husband and I live with his parents. We have the whole upstairs to ourselves. My little one just turned 4 months old and his whole family keeps pressuring me into starting him in solids. I am only breastfeeding him and when someone watches him I will let them give him formula. At his 4 month wellness checkup he had gained almost 4 pounds in 2 months and grown 2 inches! And his head circumference increased by almost 5 inches! So since he is thriving well the dr said there's no need he's doing great and even at 6 months it's just for fun. I personally do not want to start him on food, I love breast feeding him and don't want to tamper with my supply since it's been going wondering since day 1! We will see what happens when his teeth come in (which he is teething bad right now) but I plan on breastfeeding for a year or maybe more if he will have it. I never planned on BF that long before he came but now that we share this special time together I don't want to put a limit on that and they don't understand because both their boys were formula fed. Anyway to get back on track his mom said that I still need to start him on Rice cereal and such because he needs to get use to the spoon and his stomach needs too get ready. I don't see the rush for it. I'm stay at home, first time mom so I can feed him easily all day no problem. His parents have been giving him a taste of different foods for the past few months, mainly sugary foods. Whenever I say 'no he's not ready for that' or 'I don't want him eating that' they said "oh a taste never hurts". I know her parents have givens my husband's cousins little twins melted ice cream at 6 months old without telling their mom so I'm wary of them doing something of the sort to my son. It's just frustrating and hard since we all live together.

They were pushing the bottle super hard until at month or so ago and have finally backed off that. I would let my husband's dad watch him while I ran upstairs to gather laundry and I would come downstairs and he would have a bottle in his mouth! So I've have a good fight to keep this baby on the boob so far, anyone have any suggestions of comments I can retort back to when anyone says he needs real food? Without sounds like a snob and thanks if you made it through all that! I got off track a bit but I can't complain the my husband about his parents anymore or we start fighting /: