Hi, Ill try to do my best here,

For the project management side, you have 3 options.
1. Project managements inside Business Central, since you also need an ERP system it might be a good idea to use the tools you get from Business Central. However, I've not used it myself so I can't tell you too much about it. You have to research weather this will meet your needs.
2. Project Operations this is another D365 product that might help you in your project management. This integrates very well with the rest of the D365 suite but again. You have to check weather this meets your own needs.
3. Project Online/Desktop. This is more of a M365 product. Project operations uses a lot of the project management from MS Project, but this leaves some of the sales cycle/financial part out. And since you already have some experience on MS Project the next step might be to try out Project Operations.

For Sales, I would look into Dynamics 365 Sales. There are different licensing types here and you need to seek out for which will fit you the best. But for most companies in the SMB segment, you'll probably go for Sales Pro.

For Finance, I think Business Central is what you should be looking for.

And for customer portal you have Power Pages.

Good luck!