Might be worthwhile chatting to a dentist. My dd had her first teeth at 5 months than had a dental check up, part of that was checking the gums. She may benefit from having her gums checked. Not sure what restrictions are at the minute with covid though.
Was she very premature? If so it’s possible she may not teeth until really late. I think it’s a good idea to push for a pediatric referral if just for her weight. My baby was on below the 9th centile for a while and everyone was really worried - I had dietician / HV weigh-ins / pediatrician appointments every week.