I have been flying Stansted-Italy since dd was 8 weeks.
Priority boarding is your friend. Worth every ££££££.
Get to the gate early, and just stand there. You will need to pointedly wave your priority bit around as Italians will not have priority boarding but will try and push you out of the way anyway. (dp- Italian- despairs of his countrymen at airports)
It is a long way from the departure lounge to the Ryanair gates- with a pushchair it is about 10-15 minutes. Lots of stairs as well (there are lifts) I reckon there are about 4 different floor changes between the departure lounge and the Ryanair gates. Don't sit in the central shopping hub until your flight is last-called. As soon as the gate flashes up, head off. There is a WHS and cafes and loos by the gates.
Change the baby just before you board if poss and you might last the 3 hrs. You might not, but you never know. When you get on, sit in an aisle seat. (travel psychology
someone might clamber over you to get to the window, but if you are by the window, they will def bagsy the aisle seat. Ryanair do tend to fly full, so you are unlikely to have the whole row but you might strike lucky and get the middle seat spare where you will be able perhaps to spread out a bit, as the baby otherwise will be in your arms for the duration.
Take a letter of consent, google the zillion threads I'm on about this recently (travel along and used to work for immigration) you can download a consent letter from various legal websites.