Lump on gum

So my girl is 14 months old. Her back teeth are cutting through. Well on the bottom there's like a lump there. I've never felt it so big from when her other teeth came in. When I rub teething gel on them it doesn't seem to hurt her. But I'm just curious is this normal? Her top back teeth didnt swell up like that when they cut through. I noticed it yesterday. I seen a white spot on it so is that just her tooth trying to come in? I'm just worried it might be an infection or something 😑😥